I therefore took a picture (while driving, it was the only way) and looked closely. You can also see this on page 179 of the US version owner’s manual.

Instantaneous Fuel Consumption indicator on third generation Prius (in MPG)

There are exactly 20 lines divided into 2 sections each (0 to 5L/100km and from 5 to 10L/100km), separated by a dot in each section (at 0, 2.5, 5, 7.5 and 10L/100km respectively). Each line represents therefore 0.5L/100km. In case of MPG representation, each line is 5MPG. I don’t know what the km/L would look like.

When the line just underneath the central point (i.e. 5) is lit, you are consuming 5L/100km. When the line above is lit, then 5.5L/100km. When the bar is full, you are consuming 10L/100km or more. If the bar is just 1 line less than 5, y0u are doing 4.5L/100km, and so forth. Similarly for MPG.

The IFC on a HSD run car, at speeds lower than about 70km/h is not very helpful to understand how much you are really consuming. The engine charges the HV battery as well when moving the car via MG2, and this electricity is then re-used to glide at 0L/100km for some distance. The extra burned fuel is used afterwards to push the car in another way (electrically). Therefore the average fuel consumption, at these speeds, is typically well lower than what perceived when seeing the bar shooting up when the ICE fires up driving at these speeds.

For example, you will see for a minute or so a fuel consumption of 7.5L/100km (and panic, don’t you? ), but then you average it with another minute or so of 0L/100km while keeping speed constant, hence averaging maybe about 4L/100km during that time frame, and this not really what the bar is telling you.

Beyond 70km/h, the fuel consumption is in fact what you are consuming at the time, as the push produced by the engine mainly goes to the wheels and once the HVB is charged, it is only seldomly used to support the ICE – therefore the average fuel consumption mimics much more the instantaneous fuel consumption (i.e. you see 5L/100km, you will on average actually do 5L/100km).

For me therefore the bar is more to show me that the engine is on (when the  car is moving, that is – when I am not, and the ICE is running, the bar stays at 0L/100km and shoots up at 10L/100km when I start crawling forward; I don’t understand why they programmed it that why – if I am standing still, the consumption is infinite for 100km, hence the bar should be full!). And to get an idea of what is the fuel consumption at highway speeds.

Showing instead of the bar 2 numbers continuously, one with the average (that, BTW, cannot be seen on the MFD in all screens) and one with the instantaneous fuel consumption, would have been, at least to my taste, much more useful.

I would like to give a big THANKS to my 14.000 visitors (!!!) this year!

I hope I will be able to provide you with new an interesting posts in the following months. A new interesting post “Why hybrid at all?”, currently on the works, will be posted soon!

Happy New Year to you all!

P-

http://lapriusacote.blogspot.com/

The first article posted is very interesting. It provides a scientific approach about the discrepancies noted by many Prius drivers, that calculate the fuel consumption by hand to compare it to the reported MFD fuel consumption. The differences reported are in the range of 5-7% average for most users.

The article tries to address the issue scientifically and finding possible explanations to the discrepancies.

What is your discrepancy between calculated and displayed average fuel consumption per tank on the Prius? on other cars you own or have owned?

My current discrepancy based on 60+ tanks over 2 years is about 6.5%.

As I went through the list in my head, I was surprised at how many things I could spot and even surprised of some things that actually I “forgot” of the way normal cars work.

So here below the differences that a driver will encounter and experience if moving from a conventional drivetrain car (with or without automatic gearshift) and a Prius. Some might be obvious to the Prius driver, some might be of a “surprise”, and some others will be a “shock” to “normal car” drivers, as they have been to me when I first got the car, and several months later when I started thinking about it.

If you have other ideas, please let me know so that I can add them here in the list!

• lack of starter and engine noise at start-up; if the Prius engine is warm, you can move out of the parking spot without a sound; if the ICE is cold, there is no starter noise as the engine is turned on very smoothly using the powerful MG1 generator
• lack of “push-pull” effect when changing gears (there are none!); the Prius reaches driver’s required speeds at constant acceleration, smoothly, without any jerks or ICE “up/down” noise (both, due to gear shifting)
• no clutch, no gearbox (yes, again, there is no clutch and no gearbox)
• no accessory belt (all accessories are running electrically: A/C compressor, water pump, brake pump, fuel pump)
• no alternator is necessary: the generator acts also as a motor and can start the ICE when required
• compared to cars of its size and engine displacement (>1.8L) the Prius has a relatively small gas tank (45 L/11.9 gal), due also to its fuel efficiency; this saves about 10 to 20 kgs/ 20 to 40 lbs in both tank material and less fuel to be carried around
• the 12V battery is smaller than on a conventional car (its usage is essentially to turn on the computer at start up and to act as a buffer between the high voltage battery and the 12V accessories, which are not driven directly at high voltage); this saves an additional 10 kg/ 20 lbs (a conventional drivetrain battery can weigh from 10 to 30 kg /22 to 66 lbs depending on the model/capacity – an example here)
• both aforementioned weight savings help even out the extra weight due to the 44 kg/99 lbs high voltage battery
• moreover, the Prius has no CVT, though designed to feel like one; when “slipping” it is actually not slipping at all (no clutch!) and in fact it is charging the battery via MG1 in case the engine needs to be run at a higher rpm (to improve fuel efficiency) than required for the current speed or requested acceleration; ”kick-downs” are possible like on a conventional automatic gearshift, albeit with smooth transitions from low to high speeds
• the ICE, although mainly following the request of the gas pedal, might spin at a lower/higher rpm than expected (e.g. during a warm-up phase in which, at low speeds <30km/h, the ICE is essentially not providing torque to the wheels via MG2, but doing its own thing warming up as fast as possible with the lowest emissions possible)
• the brake pedal employs a drive-by-wire system, combining both friction and regenerative braking (hydraulic and electric brakes), that will feel different and act a  bit different compared to normal hydraulic-only, directly driven, brakes – hence it might not feel as progressive as on a conventional car
• 90% of the time the Prius will be completely silent at traffic lights and stops, i.e. when not moving – additional sounds might come from the electrical A/C compressor, brake and/or water pump, steering wheel, or….from other surrounding cars
• it is possible to glide the Prius without using any fuel; on conventional cars it is possible to cut the fuel to the ICE only when the gas pedal is completely released; it is not possible to let a conventional car “free-wheel”, even in “N”, without the engine not turning (e.g. to keep all pumps active); the Prius can be kept free-wheeling by applying a very small amount of gas pedal pressure to avoid the “engine brake” effect, so that MG2 can spin freely; even in “N” the ICE of the Prius will not consume any fuel (unless to heat the cabin in winter, if necessary)
• in P, the ICE will be shut off 99% of the time (except in winter only when the ICE heat is required to keep the cabin warm)
• you will hardly hear any radiator fans running when reaching a parking spot after leaving the car, since the Prius ICE will likely have shut off already since a couple of minutes while approaching at low speeds your destination
• when accelerating, the ICE, if engaged, will be run at the most efficient rpm with the highest delivery of torque necessary for the required acceleration with the least amount of fuel; the ICE will not rev up and down while shifting through gears, as there are none, potentially working in non efficient rpm ranges
• unlike start/stop systems on a conventional drivetrain car, where essentially the starter/alternator is designed to sustain way more on/off cycles than normal, the Prius is designed “from the bottom up” to shut on and off continuously the ICE; the ICE will fire only when reaching (through the use of MG1) at least 1000rpm; the ICE of the Prius will not be affected by its on/off operation
• the ICE of the Prius will essentially be off 30-60% of the time in city traffic, while on a conventional car, except when rolling to a stop using the engine brake, it is rotating 100% of the time, using fuel 95% of the time (no fuel is used when using engine-braking on a modern conventional drive train car)
• there is no reverse gear; reverse is accomplished simply by reversing the voltage on the electric motor; the ICE will only run to supply energy to the MG2 (or to the batteries via MG1), if required; this means also that reverse can be engaged extremely quickly and also while the car is still moving forward (the computer will allow this only up to a certain speed) without any possibility to break any mechanical part (moreover, the rotor of MG2 does not touch in any way its stator)
• due to the design of the dashboard without any dials/instruments, the steering wheel on the Prius is smaller than an equivalently sized car
• the Prius is designed with cabin space in mind – the bonnet is therefore pretty short compared to a similarly long car and the engine bay is smaller than normal
• to enable faster warm ups and be ready to be driven without the use of the engine, the Prius will make “noises” before turning it on (when opening the driver’s door) or after shutting it off
• the Prius ICE by design never idles; it is otherwise used, when the car is not moving, to warm itself up, to heat the cabin, or to recharge the battery when it reaches a low level (2 bars)

Prius Wiki (http://prius.wikia.com/wiki/Prius_Wiki)

This Wiki is in no way a substitute of the PriusChat Forums, rather it complements them. As information gets generated, discussed, confronted and finally agreed upon (whenever possible) on them, it can be added to the Wiki for easy retrieval.
The information should be referenced whenever possible/reasonable.

All are invited to contribute to this Wiki!

PS: I am adding information whenever I can – I tried to give it a logical structure so far, but things can and will change. For those who are concerned of possible attacks and changes that destroy the content, I can activate several levels of control. For now, I will assume that everybody is “good” and that the Wiki will self-heal, and therefore it is, for the time being, open for edits to all.

• the HSD drives the same on both cars – I have not noticed any particular difference compared to the Prius in acceleration/behaviour in the different modes (ECO/Normal/PWR-Sport or EV mode); no matter what they have written and what Lexus might say, to me it behaves exactly like a Prius
• when releasing the gas pedal the Lexus seems to roll a bit less than the Prius (e.g. a tad more regen/braking)
• the steering wheel (205/55 R16 were mounted on the Lexus) seems a tad harder than the Prius
• the Lexus is definitely quieter than the Prius – better materials and less squeaky plastic; more insulation; but when you press the gas pedal and the engine goes up in rpms, you definitely hear it also in the Lexus; it also absorbs better road irregularities
• there is no ECO light in the Lexus;
• when the ICE turns off during driving (stealth/glide mode) the EV mode green light (with the shape of a car) in the dashboard lights up
• when selecting PWR mode the right hand side of the instrument clusters changes to an rpm meter; it’s white range is up to 5200rpm (and it couldn’t be any difference since you cannot over-rev the ICE), while the red portion is there only “for beauty” – the indicator will never go beyond the white area into the red one; the rpm indicator, considering how the HSD works and since there is no real gearshifting going on, is for me practically useless (it is exclusively displayed in PWR mode…)
• if in PWR mode, the CC is activated, the left part of the instrument cluster reverts to the standard CHG/ECO/PWR dial, found also on the Auris and the Camry Hybrid; the HSI bar on the Prius in my opinion is easier and faster to “read” – it might be a matter of getting used to it
• I sorely missed the Head up display (not even available as an option)
• I sorely missed the keyless entry (not available on the car I tested – it is available as an option on a higher trim level)
• rear view visibility is probably even worse than in the Prius – it is surely not better
• the FM radio does work (it does not properly on my and many other Priuschat users as well – Toyota is aware of this and is not fixing it)
• the “DSP” menu of the radio allows only to enable/disable the automatic volume level feature; a disappointment –  I would have expected something more in the “DSP” menu on this type of car
• the fuel consumption on my test was as expected and on par with the Prius – no negative surprises, and no positive ones either
• the Lexus is clearly geared toward “driving” it, while the Prius is geared towards “saving fuel” – the software and the dashboard/LCD screen on the centre console in the Lexus are not as clear and intuitive as the Prius’ MFD display
• the Prius is more “easy to use” and the MFD is much intuitive, as the one found in the Lexus – since the LCD screen can be closed (as well as tilted), some information is repeated (like the energy monitor – in the LCD with a Prius Gen2 graphic, in the right portion of the instrument cluster like on the Camry or Auris Hybrid) or only available in the right part of the instrument cluster (e.g. the average fuel consumption)
• to select trip A or B you need to push a small plastic rod on the instrument cluster – very odd and not very technological…
• though the car tested had audio and phone/BT commands on the steering wheel, no A/C controls were available (e.g. temp setting or air re-circulation); the climate controls (dual zone is available) are only repeated on the LCD screen accessible via the joystick in the centre console
• the software displayed in the LCD screen is managed via a joystick placed in the centre console – a pointer on the screen shows you where you are as you move the joystick – looks cool, but I found it a bit distracting, since you need to point *exactly* on the buttons (which are luckily not small) on the screen, so you really have to look at it when selecting an option
• the Navigation was a bit confusing – it took me a while to figure out how to set a destination – the Navi does not offer any Live HD Traffic services, only traditional TMC service
• the LCD screen is of good quality and sufficiently bright
• at high speed one can hear less wind noises and road imperfection compared to the Prius
• rear seat and trunk space are clearly smaller than the Prius; the CT200h is also geared more to (single?) younger drivers in their 30s (money permitting) that would buy an A3 hatchback, rather than a “family”(?) car like the Prius
• Auto headlights are available
• the seat regulation is the same as the Prius (mechanic, that is) – I didn’t notice a lumbar support setting as on my Prius
• overall I find the Prius ergonomically better than the CT200h; it might well be that I am used a lot to my car, but you can use 95% of the Prius features without really having the need to read the Owner’s manual (except the Navi, granted), though on the CT200h, a read of the manual could have told me a couple of things that I did not manage to do guided by intuition (i.e. when I wanted to reset the average fuel consumption, there is no difference between trip A or B, but… there is another “hidden” average fuel consumption in the “instant fuel consumption” screen – both do not clearly state if they refer to trip A or B – likely to none…; I also could not go back to the “fuel consumption” screen on the LCD monitor – I never had this issue on the Prius in finding the screen I wanted – simpler maybe, but more efficient and intuitive)
• an “elapsed trip time” is available – I miss it on the Prius
• the HSI gives better feedback on how you are accelerating – its position in the centre console, rather than in the instrument cluster is, my personal preference, better and less distracting while driving (your eyes move less and need to refocus less when looking “far away” in the middle part of the dashboard)
• the LCD screen has only 2 screens dedicated to fuel consumption (no averages) with bars and “best”; the only other screen is the energy flow monitor Prius Gen 2 style
• since I couldn’t really drive on extremely winding roads, and I am used to a Prius with 215/45 R17 wheels, I cannot really say that I noticed an “immense” difference in handling capabilities on the CT200h – the CT is maybe a tad better, but nothing dramatic.

1. does the length of the bar change “meaning” in different modes (with obviously full up to the PWR area delivering *all* of the power available from the HSD)?
2. does the length of the bar spring up more or less quickly in the different modes? or better said – will PWR mode mean you end up in the PWR area faster with reduce gas pedal pressure? if so why? (I mean, you are in PWR mode – why psychologically have drivers think they are consuming more by being the PWR area continuously when clearly, I chose PWR, so I don’t want to save fuel!)
3. the mode changes mapping of the gas pedal, but not just that – apart from the A/C being less “aggressive” in summer and winter, PWR mode will keep the ICE on when releasing the gas – it happened to me a lot of times – it seems as if the HSD is leaving it on to provide quicker response when pressing the gas pedal again, while at the same time charging further the HV battery for the extra kick when accelerating; the ICE simply does not turn off as often as in ECO mode; so – does the engine management change with increasing pedal request? (more voltage on the MG2, valve timing change, more current form the HV battery, etc)
4. does the Prius drive normally at 500V and will enable 650V only at particular gas pedal ranges to enable more torque (or power) on the electric engine? does the selected mode change when the 650V are available?

Based on all the above, my 15 months long observations, comments on Priuschat from other forum users, and simple and likely down-right wrong assumptions, I came up with the following table and chart – attached below.

Notes:

• columns B/D are arbitrary values I assigned to make the curves look as posted on other threads here about the gas pedal mapping; colum C “normal mode” is linear – plain&simple
• HV Max voltage – pure speculation – I started by assuming that in normal you have to end up in PWR area at 70% of gas pedal pressure
• 125% is the max request to obtain the 100% output from the HSD - the extra 25% is to take care of the PWR area in the display – it has nothing to do with the overall output power and to assign 100% for a full, albeit still green 100% bar
• the 100% area will be reached – pure speculation and some personal experience but not backed up by data – at 90%/80%/60% gas pedal pressure respectively in ECO/Normal/PWR mode
• the formula to calculate values in columns H/I/J is the same and arbitrarily set as Value = (Output*HV Max)/(650*80)
• in the chart, when 100% is exceeded, HSI PWR area lits up, to the max 125% HSI bar length = 100%HSD output

Comments are welcome – it might be all wrong (likely) – it might be OK, but clearly needs a lot of polishing and data: work in progress!!! (PS: I don’t have a Scangauge!)
What are your experiences on how the HSI bar behaves in the different modes? does it react the same (proportionately to gas pedal pressure and mapping)?

Pulse, means accelerating quite forcefully (“not like a granny”) to a desired speed and then releasing the gas pedal. After that, reapplying the gas pedal in such a way that the HSI bar is not visible, thus simulating “N”eutral and “gliding” for as much as possible (limitation here is most often road type and traffic). When gliding the speed will go down, which means a new pulse will need to be performed. The higher the speed, the less this method works since the wind resistance will reduce the time a glide is possible.

If the desired average speed is, say 70km/h-43MPH, the idea is to pulse to, say, 80km/h-50MPH and then glide down to 60km/h-37MPH and then pulsing again at 80km/h-50MPH – this would yield 70km/h-43MPH average (more or less). And a headache. You need to constantly focus on the speed and on how much gas you are applying to make sure you do the “glide”. And if you live in the US, and don’t have the head-up display, means checking (especially the first few days/weeks) constantly the instrument cluster in the dashboard to get a hint from the HSI how much you are accelerating. Moreover, the overall driving experience will be not quite that smooth and that could be a problem for passengers and drivers alike feeling a continuous push-pull.

The Prius is pure smoothness, so pulse & glide, in my opinion defeats the whole purpose of it.

Moreover, the Prius has been built to be driven normally without any of the above, and yet achieve good to excellent fuel consumptions (down to or even below published ratings, that is). So I will focus here on outlining tips and tricks to achieve at least a very good fuel efficiency (<5L/100km / >47MPG, that is) at temperatures above 0C/32F, even in city traffic. These tips do not require constant check of speed, or acceleration (especially after a few days of practicing) and yield still a very smooth ride. I will not use exotic terms like “pulse & stealth”, “pulse & coast”, “pulse & glide”. I bought a modern car that should adapt to me, not the other way round.

So let’s see what a normal driver can do, to get close to the “hypermilers” (which claim to achieve consistently fuel consumptions below or well below published ratings).

Please drive SAFE at all times: it is better consume more, than having a car accident because you are not looking at the road or you are trying to squeeze the last mile from a drop of fuel!!

Driving tips:

1. This is tip number 1, and for a reason – all the tips below depend greatly on it – don’t follow this, and most of the other tips are useless or will become greatly ineffective: Drive as smooth as possible!!! Which means, within important safety limits, “like as if you had no brakes”. Think of the Prius as a boat sailing on a lake or sea, and you get the idea…(it will also do you mental health good and keep traffic stress, on the long run, low, actually lower than it has ever been in your motorised life)
2. Predict traffic: look out for traffic lights that have become red (this means, foot off the gas!) and if you know the route, learn the timing of the traffic lights, where people tend to stop to turn left or right, where bus stops are, etc. – try to memorise everything on your commute that might distrupt “the flow”: do anything possible to brake the least possible and accelerate smoothly and progressively; look-ahead of the next 2-3 cars if possible and try to avoid stops, by e.g. changing lanes, to keep the flow and avoid to stop the car when it is not really necessary; by “flow” I mean your flow, not necessarily the flow of traffic surrounding you; you will likely notice that you can keep the flow and drive at the speed limits, with other drivers zapping around you *well* above the speed  limit and breaking last minute, or accelerating without end with clogged traffic just a few hundred meters in front of you…
3. Brake progressively: [as advised from PC user giora] start braking early enough, when you have to, so that regenerative braking is used most of the time, and friction braking is used only to actually stop the car at speeds below (I believe) 7km/h-4mph; in this way if you have to interrupt the “flow” you are making the best out of it; the CHG area should be never be filled more than completely in normal braking – that insures you are not using the friction brakes – breaking more, after the CHG region is completely full, will force the computer to use the friction brakes to get the additional requested brake force
4. Accelerate progressively: key here is to exploit the benefits of the hybrid architecture and the intrisic benefits of electric engines. Try to get the car moving with the electric engine only, up to about 20km/h-12MPH; then continue accelerating to the desired speed by letting the ICE do the job (while, BTW, charging the battery). Once the HSD computer decides it need to turn on the ICE (as you will continue to progressively accelerate more), don’t be shy in getting to speed (avoid clogging traffic…), but stay out of the PWR zone. The HSI bar needs to be filled up *very* gradually. ECO mode, in towns/city traffic, is IMHO the most appropriate mode (as also per Toyota’s Owner’s Manual) as it helps you control *very finely* the acceleration requested from the HSD and the way you fill the HSI bar (it will not “jump” to the right that easily). PWR mode is instead, IMHO, detrimental, as you cannot really fine tune accelerations and the ICE tends to be on just a tad longer when you release gas, when instead it could be turned off: in city traffic likely you are not going to need or want a sudden kick when accelerating again after finished braking or releasing the gas pedal as you approach slower traffic. I would keep PWR mode when you want to have fun on non-city roads (and don’t expect to make wonderful fuel consumption averages either! though probably still better than any other comparable sized car out there…)
5. Keep on the right lane if on a 2 lane-per-direction road, so that you can do what you want without annoying anybody else – you can accelerate slowly, fast, do what you want – since you are in the right lane if somebody feels the urge to reach his destination 20 seconds earlier, or the traffic stuck at a red light visible in front of you, it can do so by overtaking you on the left lane; once starting driving with “the flow” it will be amazing to notice how many drivers will feel uneasy and annoyed by you, while you approach with no rush, the clogged traffic just sitting at the traffic light in front of you…; especially outside of the US: my belief is that drivers will be not annoyed from you having a Prius (most people have no clue what you are driving), but because you are not quick, when *they* expect you to be quick and when in fact it is blatanly not necessary at all to be quick (i.e. there is nowhere to go – traffic!!! can’t you see it?!?!?) – most commute traffic seems to be made of hopelessly frustrated drivers getting nowhere faster than they would.
6. If on a 1-lane road, be nice to others and keep up with the (traffic) flow – saving fuel while annoying other people or driving granny style to save 0.1L/100km-1MPG is simply nonsense…don’t be a drag and be reasonable whenever possible
7. Trust the HSD computer: keep “the flow” (as per tip 2), and don’t worry what the car is doing – whether the car is running on electricity only or using the ICE to keep momentum/speed it should not be of concern; the HSD computer is optimised for max efficiency for the speed you are keeping and on the load; the deal breaker for fuel efficiency is sudden/hard stops and accelerations that do not exploit the intrinsic nature of the hybrid drive (e.g. by not using the electric motor where it is most efficient, that is, from a stop); tips 1 and 4 are key here!
8. Speed is key: on highways and higher speed suburban roads, some of the tips are still valid, though the *key* factor will be speed: the hard rules of physics determine that the faster you will travel, the more you will consume (hybrid car or not…). Driving at 120km/h-74MPH instead of 130km/h-81MPH will make a visible difference on the fuel consumption average, though adding likely not more than 5 mins on your trip (depending on trip length). At speeds higher than about 70km/h-43MPH the electric motor plays progressively a minor role in keeping constant speed as the current required to keep the momentum increases rapidly (you will need a well charged battery, 5 bars or more, for the ICE to not actively push the car, i.e. driving electrically only – this means that this will happen very seldom and wind resistance will bring battery charge down fast). It is more efficient for the ICE to do most, if not all, of the work at higher speeds, where aerodynamics, traffic flow, weather and tire pressure and ICE overall efficiency will make the difference, nothing else; this also means that using CC in these cases is OK, if you like the way the CC keeps the speed (which I don’t since it accelerates too hastily when going uphill, and it does not predict what is coming ahead – on nice flat empty roads it is pretty nice though… )
9. Warm it up: [as advised from PC user sipnfuel] if your local road regulations allow it, it can be of help to keep the Prius standing about 30 secs after turning it on allowing the engine to warm up before moving the car; if regulations do not allow this (e.g. in most EU countries), drive as slowly as reasonably possible for the first minute or so. The reason for this is that the Prius warm up period at startup is geared towards enhanced exhaust quality (i.e. less polluting) rather than fuel consumption or overall efficiency – this means that the car will be moved, unless you accelerate heavily (i.e. beyond the middle line of the HSI), mainly via the battery, as the engine’s torque will only be used to charge the HV battery. After this time the engine will be warm enough, to supply some torque and hence there will be no more need to use the battery energy unless necessary (as per above tips). If the temperatures are low, the warmup period will be longer – up to 3-4 mins. The only way to know if the engine is warmed up is to stop the car (e.g. traffic light) or drive it with minimal gas pedal pressure, at speeds above 50-60km/h and see if the fuel consumption is zero or not. The warm-up of a Prius is quite different therefore compared to a conventional car, where driving it slowly *immediately* after turning it on, will actually improve the warmup process and reduce fuel consumption and pollution (the engine has to turn, so better put into use the torque it generates – there is no HV battery to charge…).
10. EV-mode – only in the driveway/parking lot: EV mode, that tells the Prius to “force” within certain limits to operate only electrically, should be used *very* sparingly – the Prius is an hybrid car, not an electric car; more about the EV mode and its possible effective usages here (in section “Drivetrain – the Hybrid Synergy Drive (HSD)”, point 4, paragraph c)

Climate control tips:

1. Winter – don’t roast it: During winter keep the climate control on Auto, 18C/64F (adjust to your liking, but don’t set it at 24C/75F and expect to achieve 3L/100km-78MPG), A/C on; you could set the temperature all way down to the last setting just before “LO” (e.g. short trip with coat on), but I have noticed that it doesn’t bring too much of a big difference in FE on a regular trip; if you are driving in city traffic, ECO here is *fundamental* as it will avoid running the ICE frequently at traffic lights, just to keep the interior of the car (feel) warm; with ECO you will not freeze, since the fan will blow slower and therefore reduce the wind-chill; the car is warm the same, but using less resources; the normal and PWR mode do not do this
2. Summer – don’t freeze it: In summer, try to keep a temperature that you are comfortable with, but do not over-do it; try setting 5C/10F less than outside temperature, and lower it until you feel OK – setting stubbornly 18C/64F or LO in summer will be detrimental to your fuel efficiency; and what is most important in summer is the dehumidification of the AC, not necessarily absolute temperatures; try things out and try to trust Auto setting
3. ECO mode? not just in city traffic: using ECO mode also outside of town can still play a role, since it will reduce the overall energy load on the HSD to keep the set temperature in the cabin
4. Cool it off, before you drive: in summer, if the car has been under the sun and you don’t have the solar roof option (lucky those of you that have it!), unless you have to leave immediately, get in and open all the windows and the trunk to let the hot air out (say for 30-60 secs) while you stay out of the “oven” your cabin has turned into ; *then* get in and drive with all windows open for about 1 min while the A/C is on and fan full blast, so to reduce as quickly as possible the vents/ducts temperature from 80+C/175+F they have reached to, to a more reasonable one (letting even 35C/95F warm air from the outside though the ducts is still cooler compared to 80C/175F and will cool them off) – likely you will need to point the vents out of your face unless you like hairdryers…;) ; finally close all windows, and let Auto do the job (most likely it will turn on air recirculation for a while, and especially if you are in ECO it will keep it on more often that you think – it is OK); think of getting a summer reflective sun-shield for the windshield: it does wonders and costs “nothing” (3-5€/$ maybe); another tip, is to try to park the car with the back to the sun, rather than the front

Miscellaneous tips:

1. Check tire pressure at least once a month, and set it at 0.1 bar more than recommended, to compensate for errors in the inflating device, air spilling out when removing the valve, and to maintain, on average, the recommended tire pressure over time
2. Turn it down: unless you want to have fun, keep the radio at a reasonable volume (e.g. 20-30 volume’s setting); the higher the volume is, the more current will be *constantly* used and this does affect FE as the HV battery has less power available to feed MG2 when necessary
3. Park lights, instead of headlights: if road regulations allow it and if you deem it to be safe (according to light conditions), keep only the park lights on (since DRL are not available, at least on the Prius sold in EU), instead of the headlights on the whole time; using headlights the whole trip when not required and when it might not add to road safety (e.g. sunny day with good visibility) will also be drain on the HV battery you can avoid; BUT safety first!

The above are not “rules” written in stone; keep it cool and don’t freak out if you cannot “comply”; use whatever drive mode suits you best (ECO, normal, PWR), nevertheless try to follow the above tips.

Again, safety first! if you need to accelerate to get out of a potentially dangerous situation, or are annoyed of somebody driving really slow, stomp on the accelerator (don’t waste time changing from ECO to PWR, just stomp!) and enjoy the power of the HSD! the Prius can really surprise you on how reactive it can be. I have noticed, BTW as a nice “side-effect”, that when driving following the above tips, the battery tends to be more charged than usual, at least on my routes/traffic – when you need the kick, that charged battery is what will make the difference.

Now a brief list of things that *do* affect negatively, in my opinion and 15-months’ experience so far, fuel efficiency:

• braking hard!
• accelerating hard! (read, abruptedly!) (i.e. without allowing the movement from a stop using just the electric engine first); accelerating from a stop so quick that the ICE will need turn on immediately will reduce the benefits of having a 60kW/80HP electric engine with max torque at 0 rpms that can, with max effiency, do the job of moving the car from a dead stop or at very low speeds compared to the ICE
• consecutive short trips, with in-between stops long enough to start a warm-up cycle (no matter how short) each time (say 1hr stop at 0C/32F) – you do this, the FE will go down
• driving granny style and trying to use the battery as much as possible to keep speed constant; keep “the flow” and let the computer decide what is best!
• being worried that the instant fuel consumption is too high and trying to do something about it by reducing gas pedal pressure, reducing speed annoying other drivers, etc. – instantaneuous fuel consumption has far less meaning in a  HSD equipped car, because when the ICE is turning it is not necessarily driving completely the wheels – it is also charging the battery and feeding current to the MG2 via the MG1: a part of the fuel used is therefore not necessarily used to move the car “right now”, but it is “saved” in the battery or used indirectly somewhere else (i.e. MG2) – average fuel consumption is what counts in the Prius!
• looking continuously at the HSI or the meters without instead focusing on traffic, speed and keeping “the flow”!
• tire pressure below recommended values – when was the last time you checked tire pressure???
• not using Auto on the climate control and forcing it into some mode of operation that might effectively reduce the chance for the computer to efficiently deal with cabin temperature; one mistake I often see on other people’s car is to close down vents as well because they “hate the wind”… wind is there because the climate control is trying to set the cabin temperature using 1 vent instead of all of them….open those vents! the climate control will reduce fan speed once the temperature is reached; if you really don’t like the “wind” not even at the beginning, point it sideways or to the ceiling away from you

That’s all I could come up with so far. Feedback and comments are welcome. This article is purposely not technical.

It is interesting to notice that many of these tips actually increase FE on all cars – the difference being that in a Prius the gains compared to a normal car, are substantial.

If you cannot or are not willing to follow the tips above, still remind yourself, in case FE is not to your liking, or as expected or lower than official ratings, that you are still consuming less than most other cars out there today (especially true if you live in the US).

Here you will find a video of PriusChat Forum User TonyPSchaefer, that describes some of the tips contained in this blog post during the HybridFest 2007.

1. the boot is not at all deep – if you think the Prius’ boot is not deep enough, you haven’t seen an Auris…
2. you can see the current fuel consumption in numbers, rather than in a bar –> consumption during full acceleration from 100km/h to max, on flat, around 17-19L/100km (12-13mpg); consumption at a traffic light accelerating in ECO mode at the limit of the PWR area, around 25L/100km-9mpg (which slowly goes down when gaining speed!); compared to the EU Prius this is much better since all you can see is a full bar = >10L/100km, but you don’t know how much up you are really…
3. the energy monitor is Camry Hybrid style – it does not show arrows going from the engine to the battery, thus inaccurate – on the Prius you can see arrows, going from the engine to the electric motor and/or directly to the wheels *and* to the battery via the motor (describing accurately how it works).
4. the current fuel consumption reports 0L/100km when standing still with the engine running – though formally correct, it does not switch to L/h like, e.g., on VW cars
5. rear visibility is not much better than on the Prius
6. overall behaviour of the powertrain practically the same as on the Prius (no reason to be any different, since both cars also weigh essentially the same, i.e. about 1440kg)
7. maybe due to the tires, tends to lean to a side when taking bends “fast” – the Prius seems to be less prone to leaning and seems to handle better the road – still, depends on the tires used…
8. average fuel consumption seems to be in line with the Prius – no noticeable differences
9. navigation system somehow confusing – happy I didn’t take take the Prius with embedded navi – I am so happy of my TomTom and it costed a fraction – not to mention that a Navi in the middle console is more difficult to look than my Navi sitting exactly in front of me behind the steering wheel.. (matter of personal preference, of course); the navigation commands are not replicated in the instrument cluster
10. no head-up display – I *really* missed it
11. conventional speedometer with pointers (?), instead of numbers – difficult to understand at what speed you are travelling – I am not used to those anymore – I like to see a number – much easier and faster;
12. MFD is small and a lot of clicking to see the information needed – the average fuel consumption is “generic” and not linked to Trip A/B – can be useful, but at the beginning I was wondering why it wouldn’t change after resetting Trip B and when switching between A and B
13. switching between Trip A and B only via mechanical switch on the instrument cluster (OMG)
14. available in MFD travelled time (also not related to Trip A / B) – I miss that on the Prius
15. FM radio works! on my Prius instead…
16. the Navi has a CD player sitting on top of a (blu-ray?) smaller slot for the Map…no SD card slot to be seen
17. also in the Auris, no way to know where the front of the car ends…
18. the switch to day/night illumination is somewhat slower than the Prius (i.e. when running into tunnels)
19. somewhat smaller inside, more “snug”
20. better look&feel of plastics
21. no historical fuel consumption “statistics” – the Prius is more geared at showing you what you are doing and “teach” you how to save gas
22. the HSI is easier to “see” on the Prius – on the Auris a gauge moves at the border of the left round instrument and there is little difference or feedback in which region you are – the Eco light monitor is a pretty small light in the center of the instrument cluster; somehow the Power area is just as wide as the hybrid+eco hybrid area – why?