Prius vs conventional drivetrain cars: main differences and subtle ones too!

After 2 years and 30.000km driven in my Prius, I have started to think “what are the differences between this car and any other conventional car out there with a “normal” drivetrain?”

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)

Thanks for PriusChat members Tideland Prius, dark_matter_doesn’t, kgall and usbseawolf2000 for their contributions!

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