Originally posted by: sinucus
So your 30mpg highway car will get 25 at 70+ and the prius 50mpg car will get 40mpg at 70+.
Yes, but that prius getting 40mpg at 70+ is essentially a 70horsepower vehicle It is getting 40mpg because it has a small aerodynamic body optimized for mpg plus a puny engine also optimized for the same.
The electric drive system exists so the internal combustion engine is only used in conditions that it is most efficient (sustained, relatively wide open throttle running). The internal combustion engine is already running in its efficient regime on an uncongested highway, thus the hybrid-electric drive does little for you and it is the efficiency of the gasoline engine that matters.
That car getting 25mpg in your example is a 140+horsepower vehicle (probably 200+hp with the way vehicles are made now). Apples to oranges. Such a car isn't really *that* efficient to begin with, although not a gas guzzler per se. (edit: I would also argue with the fact that a vehicle rated for 30mpg highway would drop to 25mpg at 70+ in the first place. The main reason for failing to reach EPA estimated mpg on highway is traffic; given a wide open stretch of highway most cars going 70+ will still hit their EPA ratings just for the fact that there is no constant braking and subsequent acceleration. Break 80 or 90 and you might have a point, but my experience has been that 70mph is no big deal for modern cars and on long drives during vacations I have ALWAYS met or exceeded EPA highway ratings.)
Make a non-hybrid 70hp vehicle, and it will get the same mileage as the prius on long highway drives if given the same body, tires, aerodynamics, etc. Heck, make a Prius, take out the electric drive components, and it will get 45mpg on sustained highway driving, it just may take you a very long time to get up to speed
😉.
My whole point is that Priuses don't get *CRAP* mileage on the highway, but their mileage on highway driving is not any better than a similarly designed nonhybrid. That 45mpg highway is nothing to brag about; it's the same thing a regular car built the same way (tiny engine, aerodynamic body, low rolling resistance tires, etc. etc.) would get.
