Quote:
Originally Posted by Daox
Looking at the 1NZ-FXE bsfc chart (from a 2nd gen Prius, I know it was updated for the Prius C but it should be similar), the engine probably runs more efficiently at the higher rpm. The lowest fuel consumption per amount of power developed is from 2500-3500 rpm. However, that higher rpm almost directly correlates to more power use. So, we can fairly safely say that going from 1100 to 2200 rpm really means you're using close to twice the horsepower to push your car down the road. This could be due to the higher speed, temperature, wind, inclines, road conditions, accessory use, etc.
A Gen 3 would definitely get better mileage simply due to being more aerodynamic. I'm not sure about 6-8 mpg better though. Plugging the numbers into our aero & rr calculator, it looks to be a difference is more like 1-2 mpg.
The best way to increase mileage at those kind of speeds is aeromods hands down. |
Gen3 is definitely getting higher MPG at that speeds, speaking from 1st hand experience. Though it is more of the anecdotal evidence, never ran back to back tests to prove it. BUT many hours at +5MPH on 70/75/85mph interstates.
I suspect that Toyota was too optimistic and the actual Cd of Prius C is higher than 0.28, or C ICE was optimized for different range. The compression ratio is different, 1:13 vs 1:13.4
here is more on difference btw Gen2 and C variants:
https://en.wikipedia.org/wiki/Toyota_NZ_engine#1NZ-FXE