Heavy foot mpg?

I don't it's possible to drive at 80% throttle for any significant time, without a manual transmission.

 

That's interesting - I never caught up with BMW having V6 engines - last I looked (admittedly a couple of years back) they were straight 6.

 

I have a Gen 3 and recently drove it a steady 90mph for a hour after refueling 1 mile from the road. My car was fully loaded with people and luggage. I averaged 35mpg. That's is worst I ever got. Normally with 2 people it's closer to 40mpg.

 

That episode was never debunked, but it is merely impossible to get worse MPG in a Prius than in a V8 4.0 M3 for the same speed/pattern.
At maximum speed Prius drives at 235g/kwh BSFC, which the V8 cannot cope, and M3 is heavier and less aerodynamic. In a track there are some brakings and reaccelerations, so the lighter car must consume less energy.
One more against a liar clown like Clarkson, there were no official measurements, only TopGear ones, which in the case of Tesla, again lied.

 

Yes, when on full throttle, regular petrol engines operate (efficiency related) much better than their part load service, while the Atkinson Prius always operate efficiently all around.
For simple questions, simple answers, with examples of delivery power:

(source BSFC charts Toyota)
2GR-FSE 3.5V6 315hp
2000rpm, 100Nm = 20kW (approx) -> 275g/KWh
2000rpm, 200Nm = 42kW -> 240g/Kwh
(best BSFC 228g/kwh @2200rpm//270Nm=80kw)

2ZR-FXE 1.8 I4 99hp MY2009-2015
2100rpm, 95Nm = 20Kw (approx) -> 220g/Kwh
3700rpm, 115Nm = 42Kw -> 230g/Kwh
(best output 73kw @5200rpm//140Nm with 245g/kwh)

I don't have acces to the M3 BSFC chart, but a sport oriented engine V8 will fare worse in efficiency when pacing a Prius.

 

i've pulled every hypermiling technique out of my bag o tricks with our dodge dakota. but no matter how i drive it, 17 mpg.

 

Let try to describe a driver who gets bad gas mileage in a Prius.
1) Always panic brake Gentle braking regenerates some energy (about 30%)
2) Drive in extreme cold. the Prius likes it warm, up to about 85F when A/C costs seem to overpower efficiency.
3) Never cruise. Be constantly either starting or stopping.
4) Drive short trips. Never let the engine warm up to operating temp (195F on my v)
5) Mess with the aerodynamics. Put a roof rack on it or at least roll all the windows down.
6) Add weight. Load it to the gills with stuff.
7) Maintain it poorly. Use the wrong oil, drive half a million miles on the spark plugs, buy gas from a station with no other customers.

I am sure others can think of mistakes they have made as well.

Now many of these actually are in use by Prius owners here, occupationally. Rural mail delivery, paper routes, pizza delivery will all get 'bad' gas mileage in a Prius. (35 to 25 MPG) it will however be 3 times what they got in their previous vehicle, driving the same way.

 

It depends entirely on the specific conditions. Under some conditions the Prius will have a bigger mpg drop, under other conditions, the V8BMW will have a bigger drop.

But the Prius will still almost always have better mpg at any given speed, except when constantly driving with 100% throttle with the V8BMW drafting close behind it.


In absolute terms, the Prius is not extremely efficient in city driving, it's the other cars that are extremely inefficient. That's because gasoline engines are very inefficient at very low power levels. So you could say that generally, the Prius has a bigger mpg drop from very low power levels to high power levels. Not because the Prius becomes less efficient at high speed, but because conventional gasoline cars have absolutely miserable efficiency at very low speed.


By the way, at a gas pedal position from around 20% to around 80% (more or less guessing here, don't remember the exact numbers, but you get the idea) the throttle plate position in a Prius is more or less steady at roughly 80% (ditto). In this range, power is mainly regulated by engine rpm, and at higher rpms also by variable intake valve timing. Consequently, with the exception of constant 100% throttle, accelerating hard in itself does not cause a big mpg drop.

So if by "heavy foot" you mean only accelerating quickly, but not constantly max., then no, there is not a disproportionate mpg drop.

 

Try towing it behind a Prius.

 

Oh, one place; driving up a ski mountain, steep and unrelenting upgrade. I hate doing that: watch the trip display mpg dropping, all the way up, and driving mostly in B mode all the way down. Tough on the car I think.

 

I can't imagine that to be any tougher on the engine than driving at 90 mph...

 

You are wrong there because the Atkinson Cycle engine is not straining at any normal rpm in the Prius.

 

I drive mine at 90 many times. It's smooth and the engine doesn't feel like it's working hard. Mileage suffers 35-38mpg. I have found the car doesn't like above 90 very much. You notice at 95mph it's starting to work much harder.

 

Unforuntely if my milege were to drop to 25 then its no better then my srt4 in winter. And i can drive it pretty hard and still get 25 unless im real hard on it then 18 baby it 30. The prius hates the cold below mid 30's, with wind & ..heat on gets 35-40. Warms up mid to high 40's with normal driving. But get better then my uncles 76 f150 w 390 auto that got 12 no matter conditions. And being pefectly flat here dosent help much either


Posted via the PriusChat mobile app.

 

Meh, even in the winter a lead foot on short trips and snow tires cuts my fuel economy for the trip by maybe 20%. The engine not being warmed up seems to hurt more in the winter.

(In case anyone asks... if you've never tried going nuts with Hakkapellitta's with TC off, let me tell you, it's so much fun... )