10 months driving in the future: a Prius 2010 review

Introduction

10 months have now gone by since I got my Prius on Sep. 23rd last year. And it has been a good 10 months.
I can now put into words these past months’ impressions, feelings, driving experiences. The winter here has been quite cold and snowy, with temperatures often reaching -10C in the morning and the summer has been quite hot until now with temps reaching 35C during the day.

Where I live, I am confronted daily with Mercedes, Audis, VWs, BMWs, cars that cost often well beyond 30-35k€, cars which often have 150+HP…

This “review” is divided into sections for clarity – there is so much to say… Take a cup of coffee or tea, because there is a lot to read…

For all official technical data about the vehicle, please refer to the Toyota Websites.
For exact fuel consumptions, please refer to tests made by car magazines and the such (a pretty good one here from Road and Track). For those reading Italian, an excellent review from Quattruote can be found and purchased here. My impressions and stats about fuel consumption below are way far from being “scientific” and are just given as an example of real life usage.

Moreover, a wealth of information can be found, for example, on Priuschat.com and Wikipedia, where some information mentioned here was found by myself as well. Other sources of information will be linked further in the text.

Exterior

Three quarters frontal view

The Prius is honestly not really a “cool” car – the design of this car is function over form and for best-in-class aerodynamics. But there are a few things that I really like – namely the 17″ alloy wheels design and the shape of the front light group. Moreover the side view and frontal-side view are the best ones, to my taste. Directly from the front the Prius does not look at all “wide” (and it isn’t). The back is still not so convincing, but way better than the previous generation, IMHO.

17" Stock Alloy Wheels

3 Red LED Side Markers

I don’t want to offend anybody, but the second generation Prius in my opinion was plain ugly. Truly a non-standard design, but it never made me skip a heartbeat… The new 2010 Prius looks really good in comparison.

BTW: I found the 3 red sidemarker LEDs in the rear light cluster really cool (like a BMW!) – I discovered them just the other day by watching the car reflection in a shop window…

Front Headlights

Colours

Not many available unfortunately: 2 whites (pearl and plain), silver grey, dark grey, a red – that is too red (and it still will not look like a Ferrari ), a blue that I have seen only once and that really did not convince me much (too “electric” in my opinion), flat black and…that’s all really, and quite disappointing.
I wanted black, but only non-metallic was available. And it was a good choice not to get it (the car looks so dull in this non-colour in my opinion – metallic would give it the “sparkle”; I have seen a couple of Prius 2010 in this colour). Dark grey metallic is what I ended up buying: it is classified from Toyota colour codes as a blue, and in fact it has a tinge of blue-purple. This colour can look plain black in the dark and plain metallic grey in direct sunlight.

Drivetrain – the Hybrid Synergy Drive (HSD)

An entire article could be written about this ingenious and yet extremely simple power train. Essentially there is the 1.8L Internal Combustion Engine (ICE) that is not connected directly to the wheels, rather via an electric motor (MG2) and a generator/motor (MG1; smaller, with way less torque than MG2 and much higher max rev speed). The MG2 drives the wheels directly at all times. There is no clutch, no hydraulic coupling, no gearbox. All gears are at a fixed ratio that never changes. The 3 motors are connected together in the Power Split Device (PSD) that nothing is, but a planetary gearbox. The “sun” is MG1, while MG2 is the outer ring. The ICE is the central planets. The computer calls on the power of MG2 and/or of the ICE according to driving conditions (accelerator pedal position, battery charge status, temperature, speed, etc) and uses the MG1 as a “buffer” between the two.

More info can be found here with a simulation, here from Toyota and again here with a nice animation. The first and last link refer to the Prius 2nd generation, but the 3rd generation Prius works almost exactly the same way.

The accelerator is not connected physically to the ICE, but rather to a computer that simply gets an electrical signal indicating how much the driver wants to accelerate (drive-by-wire). The accelerator is in fact a “torque requestor” to the HSD. The computer then decides,depending on a number of variables, from which engine the torque should be generated from, to give  the necessary acceleration requested with maximum efficiency.
The behaviour of this drivetrain is in some way equivalent to a Continuously Variable Transmission (CVT). But it is not a CVT. The ICE/MG1&2 are connected with gears with a fix ratio that never changes. Toyota calls it, for regulation purposes, an E-CVT (Electronic controlled CVT).

While driving there is no shifting, no explicit revving up and down of the ICE like on a conventional car (with either manual or automatic gearshift).

You can influence to a certain degree whether you are using the ICE or the MG2, but essentially this is not necessary and the computer will always select the most efficient combination depending on the driving conditions. You cannot, or have to, “switch” between engine type – they work together seamlessly without any user intervention.

In general, the computer will make sure that MG2 and the ICE are running in their most efficient rpms, where the most torque with the least energy can be generated. Typically this is for MG2 from zero to low/moderate rpms, while for the ICE, from moderate to high rpms. Any excess torque generated from the ICE is either used immediately from MG2, via MG1 that spins creating electricity that can be used directly from MG2, or saved in the battery for later use.
So how does this “E-CVT” feel to the driver? What happens when you turn on the car, when you accelerate and brake, when you are driving in city/highway/suburban areas? What implications/benefits and changes are there compared to a conventional drivetrain based car?
Let’s see in detail:

1. Getting in and turning on: You approach the car to enter it, touch the handle (no key necessary, as long as it is in your pocket) and as you open the door you hear a clear whir from the engine compartment. This is the first thing different from a conventional car. The whir is the brake pump starting up and creating enough pressure for the brakes to work correctly. Why? Simple: no accessories are tied to the ICE with a belt. They are all electrically driven and therefore usable at whatever degree is necessary, regardless of whether the ICE is running or not. So if your are running only with electricity, and need the hydraulic brakes to kick in, the car needs to prepare itself for it.

You turn on the car with the On/Off button and “nothing happens” – the dashboard fires up, and you hear nothing else. Silence. No starter/alternator revving up and no ICE noise. All quiet. Weird and not easy to get used to after 30+ years of conventional cars… I have turned off the car a few times, thinking that I did not turn it on at all…

If the A/C is on and it is warm/hot outside, you can also hear a mildly loud whine, not constant, coming from the A/C compressor. You cannot hear it when you drive, or when in traffic or with closed windows, or if the ICE is on. Like the brake pump, this accessory is electrically driven and can be turned on/off and tuned at will by the computer depending on needs. If you turn off the A/C, for example, the whine stops almost immediately.

In the Prius, the basic philosophy is: if you are not using it, turn it OFF.
2. Warm-up: After several seconds (depending on outside temperature, ICE coolant and engine temperature, battery charge, whether moving or not) the ICE starts a warm-up stage (more details can be found in Priuschat “Gen3 Warming Up Stages“).

First a very light whirring sound is heard, and then the ICE starts. This whirring is the MG1 acting as a motor/starter. Taking energy from the the High Voltage battery (HVB), it speeds up the ICE to about 1000 rpm, at which point gas is injected in the ICE, that fires up. The ICE is therefore always started in a very smooth way, by which oil and water have already reached the engine before getting started.

Also the coolant pump is electrical and can work, according to needs, independent of the ICE on/off status & load. The oil pump is instead (and rightly so) connected directly to the ICE and therefore will work as soon as the MG1 will start revving the engine before it is turned on (i.e. gas is being injected).

The warm-up period can be 1 to 3-5 minutes long (based on my experience), based on outside temperature and battery charge status. With a cold engine, the longest warm-up times are when the battery is empty (2 bars) and it is very cold outside. Shortest (about 1 min) is when the battery has at least 3 bars and it is warm to hot outside. If the ICE is still warm from a previous stop, there is simply no warm-up. You can essentially move out of your parking spot and get to the first traffic light/intersection electrically without a single drop of fuel.

The Prius does its best to make the shortest warm-up possible. If the coolant liquids are still warm, they are circled before running the engine.  And the exhaust gas is used to warm up faster the engine by transferring heat to the coolant liquid. The Prius tries not to waste or produce any excess energy that can go wasted.

Moreover during warm-up, at low speeds (up to around 40 km/h), the ICE is not effectively driving the wheels, rather simply warming up with “no load” and essentially dragging only the MG1 which acts as a generator and charging the battery. MG2 is driving the car at low speeds taking the electricity either from the MG1 (i.e. the ICE) or the battery. Because of this strategy, compared to a conventional car, the ICE can run at whatever necessary and most efficient rpm it requires to provide a load-free and faster warm-up, compared instead to conventional cars. It is not uncommon to notice that during warm-up the ICE noise is completely decoupled from the car’s speed. You can accelerate up to a certain speed (as long as MG2 can do the job efficiently in pushing the car) and hear practically no change in the ICE noise.

Once the engine is warmed-up or the speed is higher than 35-40 km/h you can feel distinctively that the reaction of the Prius is different – it simply means that the engine can or must now help effectively drive the car via the torque provided to the MG2.

Because no coolant temperature light or indicator is available on the dashboard, there is honestly no way to know (except stopping somewhere) to know if the engine has warmed up completely or not. The only coolant related light is a warning when the coolant is too hot (i.e. there is a malfunction).
3. Driving around: When driving, depending on a number of factors (load, accelerator positions, speed, temperature, battery charge status, selected drive mode) the computer will either use the ICE and/or the MG2. MG1 either acts as generator to create electricity for the HVB, or for the MG2 (no transfer to the HVB is happening), or as a motor to rev up the ICE (if necessary) to the necessary 1000 rpm to turn it on. The ICE can be dragged from the MG2 (i.e. the wheels) if necessary or simply idle at 0 rpm, with the MG1 taking the extra torque from the MG2 (when not accelerating), thus creating electricity converted to the HVB.

4. “Driving modes“: There are 4 “driving modes” available via buttons on the central console.

Shift Lever with the 3 modes buttons

a) ECO mode: this mode maps the accelerator in such a way that it requires more pedal pressure to achieve a certain acceleration; the A/C and heating are throttled down to avoid either using the A/C compressor too much or turning the ICE on more often than normal to provide heat to the cabin; the fan speed is also reduced to make sure that the hotter/cooler air does not feel unpleasant to the passengers (essentially the fan down-throttling, changes the “wind chill” felt from the passengers).

This mode is a huge bonus (I would say *essential*) to get Prius-like FE in winter city driving: without it, the ICE will turn on ever so often (affecting adversely FE) just to warm up the air in the cabin. The Prius is designed to run “cool”. The ICE is not meant to run generating useless excess heat, therefore in winter it has to run often, for no other purpose than generating heat for the cabin. And during city driving where often the car is not moving, this is the often the case. Normal or power mode can be used without any huge changes in FE if driving outside of town.

Why the heater is not electric, has likely to do with efficiency. The ICE can generate heat and charge the battery. An electric heater would use only the available battery charge, and the overall energy balance would be worse: the electricity used for the heater would have to be generated from the ICE in any case.

ECO Mode

Another trick to improve FE in general, is to keep the A/C temperature not too low in warmer months (e.g. 2-3 C less than outside temperature) and not too high in winter (e.g. around 18-20C). In summer/hot months (e.g. if outside is 30C+), you surely want to keep a temperature which is considerably lower than outside – I usually keep mine at 23C, but never below 21C – I don’t like driving in a fridge… In this way you can, if you want, avoid consuming resources (either battery charge or fuel) to cool/heat the cabin more than likely necessary. Honestly this is a pretty subjective topic.

But: can you really affect FE in the way you use the A/C-Heater in a conventional car? Actually, IMHO only to a limited degree: the engine will always be on, regardless of driving conditions, therefore changing temperature on the A/C will affect marginally (compared to the Prius) the overall effect on FE. On the Prius the change of the temperature and ECO mode can bring a substantial difference in FE by essentially keeping the ICE off whenever possible or not using battery charge for the A/C compressor. Moreover, extra heat not necessary for the cabin in a conventional car is dispersed in any case (the engine cannot be turned off) and in summer, though not under load, the A/C compressor is partially dragged  (but never fully disconnected) and when under load it cannot be really regulated (the Prius can regulate how fast the A/C compressor runs). Why is the A/C compressor electrical and battery driven? because it has to run also when the ICE is off (e.g. at traffic lights).

PWR Mode

b) PWR mode: the response to the accelerator is geared to provide a very prompt response; the A/C and heater work normally; I noticed that the ICE tends to remain on more often to provide extra charge to the battery (to be able to provide energy to the MG2 for prompt accelerations “at all times”) and to avoid the (though quite short) lag that can be experienced while the ICE is turned on from the MG1 under strong accelerations. This mode is especially good for highway driving (particularly in Germany… ) or for “sporty/reactive driving”.

c) EV mode: my impressions on this mode are a bit of a mixed bag; it is not yet clear to me if this is more a marketing toy or really something useful. If your battery is “empty” (less than 3 bars) you cannot use it at all when the ICE is cold, otherwise you have 1 bar available before the ICE is turned on; if there is enough charge (more than 3 bars), you can delay the warm-up phase at cold start, if you are pressing the EV mode button soon after turning on the Prius; if you wait too long and the ICE starts to warm-up, there is no going back – the ICE will continue to run until it is not warm enough; the only solution is to turn off the car – not a sensible/practical idea…

EV Mode dreaded "not available" message

If you are “lucky” and all conditions are met, you can effectively use EV mode to move a car from 2 places within a parking lot, to move a car in a garage, to arrive quietly at night in a neighbourhood/garage if so desired, or if you need to move the car for some other reason (e.g. to wash it in the driveway). I haven’t found any other practical uses. Moreover, EV-mode uses obviously battery charge that then needs to be replenished sometime later by the ICE. Oddly enough Toyota advices not to use the EV mode on a regular basis…

EV Mode - when you can access it...

And, you can drive “electrically” by adjusting the gas pedal pressure – a light touch will enable you to drive electrically (battery charge permitting) without the need of the EV mode button. Put it this way: the EV mode button is simply to tell the Prius “run electrically as much as possible, if I am not pressing too much the accelerator and there is enough charge to start the EV mode”.

d) Normal mode: when none of the above modes is engaged, the Prius is in normal mode; this is fine, in my opinion, for suburban driving

Normal Mode

Full power is available in all modes (flooring the pedal will provide the same acceleration and all available power coming from the ICE and MG2, as you can also see here in the “0-60mph ECO vs. PWR” Priuschat post ), but apart A/C & heating, also battery charging, ICE,  and electricity fed to the MG2 will be managed differently in the first half  to three quarters of the accelerator pedal position – this is not documented, but it is my strong personal impression. I clearly notice that the ICE has different sound to it (different valve timing?) when the pedal is pressed lightly compared in PWR/Normal mode compared to ECO.

Whether this is related to the required acceleration is difficult to judge. There is no rpm indication in the dashboard and the Hybrid System Indication (HSI) bar, will be of different lengths depending on the mode selected. In ECO mode the bar will reach the red power zone with less gas pedal pressure than in PWR mode – plain simple. I.e. a bar of a certain length has a different meaning whether you are in ECO, normal or PWR mode.

So, although the overall available power is always accessible, it is not clear and documented how it is distributed and how and if the engine management will decide to handle available “energy” for the first three quarters of accelerator pedal position. I.e. if the same torque is requested (clearly with different pedal positions), is this request handled differently from the HSD depending on the selected mode? It is my distinct impression that this is exactly the case.

5. Driving a Prius “ecologically”: Though it is plain clear that the only way to be ecological with regards to a car, any car, is to walk, ride a bike or taking public transportation, on the Prius there is an Eco Driving Indicator Light (“ECO light” for brevity) that helps you further in being “eco” by indicating whether you are driving efficiently or not, that is, whether you are asking for accelerations that can be efficiently be served by the power train or not (i.e. wasting fuel(?)). The Prius Owners Manual reads that if the ECO light is off it:

“Shows that an environmentally friendly driving range is being exceeded (during full power driving etc.)”

When driving faster than 143 km/h the “ECO” light in the dashboard will be permanently off, regardless of gas pedal position: you are not being environmentally friendly, you are driving too fast, you are polluting – end of story. The same happens at all speeds when PWR mode is selected (which for me is another indication that the HSD will use more fuel for better performance, compared to other modes – otherwise keeping the ECO light off is simply a marketing/psychological gimmick – I hope that Toyota Engineers are smarter than this).

How exactly keeping the ECO light on at all times during driving affects FE or HSD engine management is not known to me at this time and the user’s manual is of no help.

6. “Driving like a granny will not help FE!”: this statement is actually true, based on my experience. The best way to drive a Prius is to simply, ehm….drive it! The HSD will do its best, based on your driving patterns, to improve FE.

The best way to improve FE on the Prius (apart from using ECO mode when applicable) is to look at traffic and anticipate its behaviour. Avoiding strong braking, strong accelerations, and making sure to have an overall smooth ride will yield excellent FE. BTW: this is the case also on conventional cars…

It is quite easy with the Prius to get a “smooth” ride, since there is no gear shifting going on, so no jerking or jumpy acceleration pushes.

Depending on the acceleration/torque requested, the ICE will always run at the most efficient rpm, independently from wheel speed. It is actually advisable to accelerate “briskly” without flooring the accelerator pedal (traffic permitting) at traffic lights (while keeping the ECO light on) and to brake as gently as possible to avoid using the hydraulic brakes (and thus wasting kinetic energy in heat).

A very nicely done video describing how to drive the Prius to get good FE is available here. Essentially, predicting traffic and by carefully “playing” with the accelerator pedal to “trick” the HSD, can guarantee very good FE in all conditions. If you are only going up a hill, though, don’t expect 3L/100km-78MPG!

7. Prius “Magic” & “Happy Mode”: When starting from a stand still, the Prius will move forward (accelerator position permitting…), using only MG2 as this is the most efficient thing to do. (BTW: In PWR mode this is almost impossible to achieve, you need a *very* light foot).

When the speed increases above 20-30km/h and depending on accelerator position and battery charge status (including mode selected), the ICE will be turned on and either will assist MG2 or completely provide the torque to push the Prius forward. Once the desired speed is reached, one should completely or almost completely release the gas pedal and depress it again gently to keep the reached speed (as per user’s manual).

And this is when the Prius “magic” begins.

Depending on the desired speed, load (road steepness) and battery charge, the computer can decide to do one of the following 3 things (from my observations):

1. Use only MG2 and the energy in the HBV to provide enough torque to keep momentum and let the Prius move forward while consuming no gas. This is what I call “electric mode”, compared to the true “EV mode”. This mode can be achieved up to speeds of about 70-75km/h depending on various conditions and will average over several hundred meters (I could never check exactly for how long) a nice 0L/100km to whatever fuel consumption you have had so far.

2. The ICE is kept at an rpm at which it can a) generate enough torque to push MG2 (i.e. the wheels), b) generate via MG1 enough electricity to drive MG2 as well as c) charging the HVB. This is especially true for higher speeds and with inclines or counter wind.

3. The ICE goes into what I call “happy mode”: when the speed is “right” (I haven’t identified a range of speeds yet when this happens) and the load low enough, the ICE can drive directly the wheels (MG2 will spin at the same rpms as the ICE, but not draining any electricity at all from the HVB or MG1) and at the same time giving torque to MG1 to charge the HVB. This is a high efficient state in which on flat roads the instantaneous fuel consumption shows between 2,5-5 L/100km depending on load. BTW: this mode is not documented in the Energy Monitor description on the Prius Owner’s Manual.

"Happy mode" (sorry for the shaky pic!)

Mode 1) in town pushes up FE drastically – there is nothing more effective than averaging overall fuel consumption with 0 L/100km… The battery charge can be replenished by the ICE when starting at the next traffic light (this is why it is better to provide a brisk acceleration rather than crawl hopelessly to try to move only electrically while likely irritating other drivers; flooring the accelerator though will not help FE).

Mode 3) is the best mode in suburban areas as it provides the lowest fuel consumption, while at the same time charging the HVB. In mode 3) you can truly appreciate the effort of Toyota engineers to make a super efficient ICE and highly aerodynamic car.

Mode 2) is the most common when driving fast on the highway (more than 120km/h). In this case there is a “dance” of electricity going to and from the HVB to MG2 and MG1 to provide additional torque when accelerating and to make sure the battery is always full for extra kick or to keep battery charge to a safe level (overcharging a battery does reduce its lifetime).

8. Driving (fast!) on the German Autobahn: I was pleasantly surprised that although the Prius 2010 is an “eco car”, it can show some muscle when driving it fast. It is not designed with this objective in mind, and the top max speed of 180km/h indicates that, but it is far better than the previous generation that clearly lacks in this department.

The engine is limited electronically, so you can essentially floor the gas pedal and reach max speed without worrying of damaging the drivetrain. The max speed I have ever reached on the Autobahn in Germany has been 193 km/h and I was not at the end of it. I had to brake… The official max speed of the Prius is 180 km/h, and when you factor in a 10% error at the speedometer, a displayed speed of 198 km/h is theoretically possible.

What is nice for me is that at speeds around 150 km/h the Prius is still somewhat responsive and very stable (tried both with the stock 17” and the 16” winter tires). The only “annoying” thing is that the ICE does get quite noisy. But after all, the Prius has not being made with “racing on the German Autobahn” in mind…

You can read more about Autobahn High Speed driving with the Prius here: Driving the Prius 2010 on a German Autobahn…

9. (Regen-)Braking: Each time the gas pedal is released, the MG2 will work as a generator (like all electrical engines do) and will re-charge the HVB while slightly braking the car. Because the Prius does keep well momentum (i.e. less drag on the drivetrain due to lack of directly driven accessories, no gearbox, excellent aerodynamics), you can slow down to distant traffic lights while averaging a nice 0 L/km (like all other cars) and at the same time re-gaining energy by charging the HVB. On a conventional car, the energy will be 100% lost into heat due to friction (from the drivetrain). On the Prius a portion (conversion to and from forms of energy is never 100% efficient) is instead used to charge the HVB.

Whenever actually braking (pressing the pedal, that is), the MG2 draws even more current charging the HVB, and the hydraulic brakes (always ready) are activated only depending on the brake pedal position and speed – below 7 km/h (I believe) the hydraulic brakes are engaged in any case (friction brakes can stop the car and keep it steady, an electric engine cannot – see trains or trams).

More information on regenerative braking here on Wikipedia.

10. At traffic lights/stopping: when you approach a traffic light or a stop, most likely the ICE has already turned off – this means completely off – it is not even turning anymore. If you are in PWR mode the ICE will not necessarily turn off when you release the accelerator to keep response faster should you accelerate again before stopping.

So, when the car stops, you find yourself surrounded by blissful relaxing silence. The first few days/weeks of driving the Prius I almost panicked when I heard the engine turning off. You think “OMG, it died on me – now I am stuck here”. Relax! it is supposed to work this way. Even after 10 months I have had the same weird feeling a few days ago. It is very hard to get rid of 37 years of listening an engine running *all* the time and when it would stop it would only mean trouble.

A benefit of keeping the engine off, is also that the coolant fan is running far less than in a conventional car. I have actually never heard it run. For example, most of the times you get to a parking spot, the engine is already off since likely a few minutes – there is nothing to cool off, the air flowing to the engine while driving electrically is already cooling it off while you approach an empty spot.

Today I was in a typical stop&go situation and I could hear the fans of the car behind me and the one next to me “roaring” while we were standing still. The Prius was there, quiet, even with the AC on. Sometimes you hear noises in the Prius that are not from the Prius at all – is from the other noisy cars outside “doing things” all the time.

All this means, saving energy: energy that can be used in moving the car around instead of moving the fans when in fact you would not have to. The Prius runs cool, end of story.

11. Down-shifting/engine braking: If the battery becomes fully charged (all bars light up) while the gas pedal is released (e.g. going down a long hill), the ICE will freewheel (no gas injected) acting as an air compressor (exhaust valves are kept closed), by releasing excess energy as heat. In this way the ICE offers resistance and therefore braking power, without involving the hydraulic brakes.

The same happens when the B mode gear is selected or when downshifting on a conventional drivetrain. Using B mode gear in normal driving situations is not useful, since energy that could be used to re-charge the batteries is instead wasted in heat generated by the engine which is compressing air…so though one might be led to believe that when breaking the engine is also involved, no extra energy is actually recuperated, rather wasted. Prius drivers, drive in “D” except when “falling” down a hill/mountain

Battery fan air vent bottom left of the rear right seat

12. Batteries and voltages: There are 3 voltage domains in the Prius and 2 batteries. As mentioned above there is a high and low voltage battery (HVB and LVB) respectively delivering currents at 201.6V and 12V. The third voltage domain is the one of the electric motors, running at 650V (this is the voltage range is often used by trams and subways – when I drive next to a tram I always think of them like distant cousins ). The LVB is charged from the HVB. Each time energy is going to and from the HVB and the motors a conversion takes place – this conversion is never 100% efficient. Therefore electricity generated from MG1 which is used immediately by MG2 is the most efficient.

When the battery shows “full” (all 8 bars are lit), it is in fact only 80% full, when “empty” (2 bars left) it is actually about 30% charged. The HSD will never allow the battery to go above or below these limits to make sure the lifetime of the NiMH battery is a long as possible. A fan makes sure that the HVB is kept at a low enough temperature. You can see in the picture  the air vent close to the right rear seat.

Final considerations about the HSD: One thing is still not completely clear to me about the Hybrid Synergy Drive though after all these months.

The ICE can theoretically (within limits of the MG1 max rev speed) spin at any rpm independent of what the wheels are doing (e.g. speed). The ICE is not directly connected to the wheels and the MG1 acts as a “clutch” or “buffer” to the MG2.

So then the question is, why do I really need to accelerate “briskly” to get the ICE in the most efficient rpm range like on conventional engines, since the ICE could theoretically spin at whatever rpm it pleases independent of the wheel speed? Does the computer set the rpm always at the most efficient range, depending on a number of factors or not (e.g. speed, gas pedal position, etc.)?

If the HSD is really running/can run the ICE independently to wheel speed, then you could really simply drive the Prius as you like and accelerate like a granny, if you wish, still getting the best fuel consumption, according to your driving style. Maybe “granny style” can yield a better FE compared to “brisk acceleration” style or “normal traffic aware” driving, but maybe with marginal improvements. How much does acceleration style affect really FE? Many on Priuschat claim/report that using for example PWR mode yields them the best FE. And this mode enables an acceleration style that is far from “granny” or “normal”…

I have not yet seen a documented comparison case on the forums about what the ICE does in terms of rpms, dependently on requested acceleration. My experience is also not good enough to judge this. But I have noticed sometime that if the battery is, for example, not that full, the ICE would spin more than, with the same pedal pressure and same speed, when it is more full. That is, I have noticed that sometimes the ICE will spin at different speeds, at same wheel speeds, with the same gas pedal pressure. Something a conventional car cannot do.

Shift Lever

Toyota calls it “Shift Lever”. To me it looks like a (modern) automatic gear selector. The truth is that it is a joystick that selects the direction you want to drive (forwards or backwards) and a 2 other functions.

The shift lever has 5 positions: D, N, B, R, and rest position.

Shift Lever - why is "P" a separate switch?

“P”ark is, for some unknown reason, beyond any imaginable theory, a separate switch and not integrated in the shift lever, like on all automatic conventional cars. Why it is not integrated in the gear selector (and there is an empty position to do that!) is beyond me.

Moreover, P is automatically selected/engaged when you turn off the car.

“D”rive is the normal “every day” position.

“B”rake is the position necessary when going downhill and the hydraulic brakes need to be offloaded from unnecessary strain (similar to “down shifting” on a conventional car).

“R”everse, is to back up. For some another “unknown reason beyond any imaginable belief”, by default the Prius will beep (only inside the cabin!) incessantly as long as you are in “R”. It can actually drive you insane, which means dealers should (and can) disable it to “single-beep” function at delivery. They should also charge you nothing when they do it. This beeping is, I am sorry to say, truly Japanese madness.  Once you have the setting changed, when you select “R”, it beeps once, and you can keep your sanity while making sure you are not running over somebody or about to bump into another car or the usual absent-minded bicycle or passerby (texting or listening to music while observing the sky) while reversing.

“N”eutral is essentially a simulation, since the wheels are never physically decoupled from the drive train (remember? no clutch!). For this reason N, although it can be officially engaged at any speed, it can result in damage (I read this on forums; is that true? up until what speed?) of the MG1 that needs to offset the MG2 that will still continue to rotate while ICE should stand still. I don’t know if at high speed the ICE would need to spin, to avoid damaging the MG1 spinning too much, by using fuel and keep the “N simulation” running. When N is selected any gas pedal pressure will be negated. Because the MG1 needs to be engaged for N to be simulated, the mode will not be entered instantaneously, but after about 3 seconds of constant pressure of the gearshift lever. This is also to avoid inserting N by mistake while driving.

Cool benefit of the shift lever and the HSD: because the shift lever is nothing but a joystick and because to change the direction of the Prius all that is needed is to change the flow of current in MG2, parking is extremely quick. You can switch between R and D as fast as you can. Actually the HSD is “waiting” for you when you change from D to R. The switch is instantaneous as there are no mechanics involved and I personally find this really cool! I have never driven an automatic where I could change direction so fast!

Another cool thing is that because the HSD has no gears, when you accelerate power is delivery progressively, no matter what. No gear shifting, no jerks, no engine racing up and down while shifting gears. You want to leave all others behind at a traffic light? Bring it on! As soon as it is green, stomp on the accelerator and enjoy the immediate transfer of torque to the wheels and continuous progression while others are still shifting from 1st to 2nd gear (this applies to most automatics as well, even those with double clutch – no matter how fast, they need to change gears). And feel the awkward sensation (at least for me) of an ICE that it is self feeding its needs of power by having MG2 being fed with current the ICE itself is generating via MG1 (plus what is coming from the battery) – now that I think about it, this is a bit similar to how a turbo charged engine works…

Obviously, at traffic lights – safety first!!

Interior

Thanks to the HSD and pretty low rpm of the ICE, the interior is extremely quiet. But insulation is not perfect. The Prius is not after all a Lexus or a Mercedes. This means, that wheel rolling and ICE noise can easily reach the cabin. Certainly compared to a conventional car less insulation is required since at medium to low speeds, the drive train is *really* quiet.

The plastics are of good quality but can be perceived as a bit cheap – especially the glove compartments covers. The new Auris Hybrid (as well as its conventional drivetrain version) for example has a “soft” dashboard plastic that looks and feels great in comparison. The Auris interior looks much more “higher class” compared to the interior of the Prius; sorry to say that, but the Prius interior can look “cheap”, like the one of a Yaris…Moreover, the dashboard plastic seems very prone to scratches…tough unscathed so far…

Other than that, the interior is very pleasant, the seats are very comfortable, with very soft and sleek fabric (at least in the trim I got).

"Spaceship-like" central console

Central compartment LED light

The central console is very innovative and many have told me the car looks like a “space ship” The only drawback of the console design is that the central compartment beneath it is not easy to reach and in the dark it is completely black – a serious design flaw. I had to install an LED light to see something when driving at night. Toyota made a “big” mistake here – they should have added one single LED to have some light shine on the compartment.

Central dome ambient while LED light

There is foot well lighting, so why keep this central compartment completely in the dark? On the other hand, the central console is lit up by a pleasant white LED ambient light. This is also likely due to the fact that the gear selector is not illuminated (why?), therefore the necessary illumination from above.

There is plenty of room space both at the front and back seats. The trunk space is quite big, though not particularly deep; this can be improved by removing the bottom cover, that gives an additional 10-15 cm of depth. The best thing is that the trunk bottom surface is flat and can be used effectively. There is no indication that a big high voltage battery is somewhere inside the trunk.

Roomy and regular trunk

The trunk is also where the 12V battery (low voltage battery, LVB) is located. This is the battery that runs the accessories when the Prius is turned off (and the On/Off switch is in Accessory mode). The 12V battery is smaller and less powerful than in a conventional car since it is not devoted in any way to the energy supply of the drivetrain (which runs off the HVB instead). This also means that running the radio for a “long” time with the car in Accessory mode is not advised (though I would need to verify this statement – i.e. how long before I drain the LVB completely while listening to the radio? BTW, I wouldn’t know how long that would be in a normal car either…).

The side pockets are pretty small, and the central arm rest compartment, though roomy, is not easy to access (especially with your right arm…). Moreover its internal movable tray is not really useful – when you lift it the contents can easily fall in the compartment below… another design mistake, in my opinion. The tray is intended to keep the iPod in place, as I have seen in a picture, when connected to the radio with the USB connector (which I didn’t get as I deemed it too expensive), but it is pretty useless otherwise.

Sunglasses pocket - is it big enough for your glasses?

There is a useful sunglasses compartment in the middle dome console. I use it mainly to keep some papers, but many in the Priuschat forum have complained that it is not big/deep enough for any reasonably sized pair of sunglasses, especially if very thick when folded. I don’t have sunglasses and do not keep glasses in there, so I cannot really judge this.

The sunshields have both a vanity mirror that is illuminated when the protection slider gets opened. The thing that is lacking is a band to insert toll receipts, a map or any other paper/document. Another design mistake IMO.

1970s trunk light

All interior lights, except the foot well and the dome located ambient lights are conventional light bulbs. Though these lights are not turned on for a long period of time, thus not affecting in any significant way the overall “energy balance sheet” of the Prius, they make the car look not technologically advanced as I would have expected. Especially the trunk light: it seems coming directly from a 1970s model. I don’t know what savings they have achieved by doing this, but I would pay gladly 20-50€ more to get all LEDs for interior illumination, instead of 100 years old light technology. The same goes for the license plate lights, both light bulbs. It is all a bit disappointing. I might look for an LED replacement in the future (clearly only if this will not void in any way the warranty).

Dashboard

The first impression is “wow – this is Star Trek”; after a while you realise that the dashboard, although sporting a sleek, innovative and ingenious design, is realised with very traditional and reliable technology.

Left part of the MFD - a ghost image is clearly visible

The screen is divided in 2 sections, the right part is the Multi Function Display (MFD), which is essentially a very “1980s” vacuum fluorescent point matrix display. It is highly readable in all light conditions (a light sensor takes care of that pretty well). The colours (essentially green and red) are not perfectly fine, but OK. The other half of the display on the left is comprised of 2 portions. One which is showing speed, tank level and instantaneous fuel consumption, is “always” on and is a normal vacuum fluorescent segment display as well. Like the one you used to have on your VCR 20-30 years ago. Very reliable; but very retro as well. It is located underneath the dashboard itself and its information is projected via reflection to a semi-transparent mirror on the dashboard and then to the cabin. The second portion is another display (likely white LEDs behind colour filters) behind the mirror, that lights up almost in a “holographic” 3D fashion, when the wheel commands are touched (“Touch Tracer” function – this is standard in all Prius versions). A section of the 1st portion of the display is turned off when any command on the wheel is touched to enable the second portion to overlap gracefully with the remaining information. The overall effect is very nice and effective!

Left part of the MFD - superimposed with Touch Tracer

Because of the semi-transparent mirror, especially when first driving the car soon after delivery and you tend to check everything, there is a very noticeable ghost image of the first portion of the left side of the display. This is something that will need to be fixed in future versions in my opinion as it makes you think that the display is not sharp or there is something wrong with it or its assembly. The reality, though, is that in real life driving you don’t notice anything, and the overall display is extremely well readable in all light conditions (I couldn’t say the same of the Prius 2nd generation).

The MFD shows several screens, which are (in no particular order): Settings, Rear Seat-belts monitor (turns on if a back door is opened; 3 dots show seat-belts that have not been buckled up and help the driver understand if back seat passengers have buckled up at all or not; there is no seat sensor, so the screen will show up even if nobody is actually sitting at the back – you just need to open a rear door once for it to show up: ingenious and cost effective solution); Energy (flow) Monitor; Hybrid System Indicator (HSI – a very detailed on the information provided from the HSI and its meaning here); fuel consumption overview (for Trip A and B separately, in 1 min or 5 min periods), fuel consumption history for Trip A and B (a column displays each Trip A or B before a reset is done on the counters).

The HSI indication can be displayed together with the speed on the head-up display (HUD). The HUD is a really cool feature offered standard in Prius sold in Europe. This feature is not even an option (why???) on the Prius sold in the US market. If Navigation/GPS is available, the HUD will also show direction information as well. The HUD has settings for brightness and height. It is particularly useful to keep the eyes on the road while checking the speed.

It is interesting to notice that Toyota thought best to have HUD standard (at least in Europe) rather than LED lights (as per above comments) for interior lighting. Weird cost-related choice..

My experience is that after the first few weeks, the HSI and Energy Flow screen become essentially “useless” since you can easily map your accelerator position, driving behaviour and engine noise to the information on these screens in your head. Whereas the fuel consumption overview shows what I think it is really necessary: fuel consumption average for the selected trip (not shown for example in the Energy Monitor screen), and ECO light (i.e. you are not accelerating “too much”). Since the Prius does a great job in managing itself, you do really need to focus on the traffic and how you drive, rather than looking at the MFD the whole time. I got my best FE numbers, when *never* watching the MFD…

Radio

The overall radio and speaker stock setup (8 speakers) is quite powerful and performs well. Bass and high tones are reproduced clearly and with little to no vibration of the interiors at mid-high volumes. The radio is equipped with automatic volume level (3 level settings are available), that increases the volume when the speed of the car increases to compensate for external noise.

There is one thing that hasn’t been working properly and I have notified Toyota of this months ago but it is yet to be resolved. When listening to FM radio stations and the car is moving there is a constant background clicking and popping noise disturbing the listening experience. I cannot essentially listen more than 5 seconds of noise-free radio, even in areas where reception is excellent. Actually reception of the Prius is better than my previous car’s radio, and picks up signal also in location where previously my other radio would simply not get any. It is a pity that there is this issue with the noise, since overall I would be very satisfied with this stock radio.

Performance & Fuel Consumption

In my daily 18km (one leg) commute in town (with traffic lights, stop&go traffic, high speed (up to 70km/h) sections) I got an average of 4,8L/100km in Winter (with winter tires mounted), down to about 4,0L/100km in summer (with 17″ stock tires on alloy wheels). Compared to my previous 1.4L TDI Polo: I am consuming in winter with the Prius, what I would consume in summer with the Polo. In summer I am consuming an average 1L/100km less; on suburban drive, I would consume with the same weather almost 1L/100km less than the Polo on the same route; on the German Autobahn they consume the same (about 8L/100km at 150km/h – but check this post on Priuschat.com for details – Driving the Prius 2010 on a German Autobahn…).

And this is even more impressive considering that the Prius: is 81% more powerful (136HP vs 75HP), achieves 0-100km/h in 24% less time (10,4s vs 13,6s) although being 18% heavier (1470kg vs 1248kg) – despite this, it consumes on average 16% less fuel (based on official data, not my findings) and generating 24% less CO2 than the Polo.

So what about everyday driving performance? ECO Mode wades down things a bit – clearly. You need to push more the accelerator pedal to get a bit more kick. But if you want to very finely adjust gas pedal response and calm down your F1 driver instincts when absolutely not necessary (in town, that is), ECO mode is perfect.

Normal mode is, well, normal. And the Prius feels like what a 1.8L car would feel. With a twist. The 207Nm provided by the electric motor makes the reaction from standstill quite interesting.

Select Power Mode and it feels like you have another car altogether. It is like as if the Prius becomes truly aggressive and shows the muscles of the combined power from the hybrid train. And this is what makes this car even more special. The previous Prius version was a very dull car, the new Prius can show off its power, albeit improving overall fuel consumption.

The HSD is smart enough to keep fuel consumption in control in all modes, but in Power Mode, at least for my experience, you tend to consume 5-10% more if you are using it in town. On the highway, if you drive faster than 130-140km/h it honestly makes no difference in terms of fuel consumption, but still providing the necessary kick when necessary. And this was actually my biggest surprise – although the 1.8L Atkinson cycle engine is not a supercharged beast, with the help of the electric motors, is still surprising reactive even at high speeds (>150km/h).

Conclusions

The Prius (and all Toyota full hybrids currently available worldwide) have changed the way cars move around this planet. They overcome and improve the 100 years old conventional combustion engine concept deficiencies (namely, the lack of efficiency and torque at all rpms) and compensate using intelligently an electric motor. It gets away with the old and obsolete single 12V electrical network, splitting (as every minded electric engineer would do) it in 2 more efficient networks; higher voltage for the previously run engine accessories (pumps, A/C), and lower voltages for in-cabin ones (radio, lights, etc.).

The HSD system makes sure that things run *only* when necessary and to the rate requested. The ICE is turned on only when necessary, and all generated energy used with as little waste as possible.
Driving an HSD powered car, means finding oneself all of a sudden in another world. Standing in light at a traffic light, surrounded by cars making noise and polluting with no reason (start/stop systems are, finally, making their way though), is almost an unreal experience. A traffic jam is now only a waste of time. And actually it can even improve your FE if the battery is charged enough and outside temperatures and jam length are not excessive. You start going less to the gas station. You start enjoying driving much more. The lack of gear shifting, coupled with transmission that delivers power directly like on a clutch driven car but without any jerks or engines revving up without reason (inefficiently, that is) and simply enjoying the wave of power coming continuously from the HSD, is a new concept in driving (at least for me!). It feels like being on a train or a boat, sailing quietly through traffic.

And you start enjoying again the silence – driving a Prius can be a relaxing experience because you are surrounded by silence and you know that this is also saving you money, the environment and the air people breathe, especially when driving in town.

Sometimes I get the odd look from passers-by when I move my car silently in car parks or driveways. And you see they are baffled and at the same time curious to know how it would be to drive a car like that.

A word about “hybrids and electric” cars being too silent and pedestrian safety: well, first and foremost, conventional cars are too noisy Once this is cleared, let’s get to the point.

I live in EU and in Germany where there are a lot of pedestrians and bikes. A lot.

Simply put, pedestrians are not looking at all when they walk, they don’t listen to the surroundings when approaching a road or crossing it most of times. They live in a parallel universe called “my own business”. I had to honk often pedestrians not looking what they were doing when crossing roads “when/where they wanted to”, while being on mobile phones SMSs, chatting along, listening to music (making them deaf to anything else) and simply minding their own business forgetting that they are part of traffic. This was when driving a noisy diesel (yes, it was *noisy*) – not the Prius. Same goes for bikes.

The Prius is a big car, and unless being blind, you can see it moving. If you care for your safety and are crossing/walking where you are not supposed to you look for things on the road that move (i.e. cars…). The problem is not that the Prius (or EV vehicles) are too silent, is that pedestrians and bikers are too distracted. Drivers are distracted as well, but that is another story.

Regarding blind people: blind people use noises/sounds as cues to know what is surrounding them, but because they know they have to take special care in what they do when outside closed environments, they do check and pay attention (as a normal pedestrian should do and actually doesn’t most of the time). When the Prius rolls to a stop with the ICE off, it still makes rolling noises (like all cars) and some high pitched sounds coming from the inverters, the electrical motor and the brakes. Some conventional cars have become so silent that I have noticed that I only hear the rolling of the wheels when the engine is not pushing the car.

Blind people, as well as their trained dogs, do use hearing way more and notice what normal people don’t or cannot hear. I think a moving Prius, makes less noise than a normal car when rolling to a stop, but it is certainly not so silent to be a threat to blind people or pedestrians.

In the meantime I need to continue to turn on the emergency flashers when driving out of a parking spot to make sure that bikers, pedestrians in the middle of the road and cars *see* me instead of wandering off, day-dreaming and looking the sunshine and the fluffy clouds in the sky.

Bottom Line

If you are looking for a car that will change your driving experience forever, that will make you feel relaxed, in control of the fuel you put into it and want to break forever from the clumsy vehicles surrounding you, riding the future, the Prius is the car for you. After driving this, you will never want to drive a car without HSD ever again. The next step will only be, a fully electrical drivetrain car.

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