It does.
Not in that engine (which is identical to my car's).
IMHO, the Corvette engine acts just the way an Otto Cyle engine should act (see below). The key issue here, I think, is the difference between engine efficiency and vehicle fuel economy.
There's no need. As I mentioned before, '92-up Corvettes can display "instantaneous" and distance-averaged mpg, which have proven quite accurate in my car. On several road trips, I've set the cruise at 100 mph while driving across a desert (pbutting dry & salt lake beds that are very close to level grade), zero the average mpg, and check it when I finally have to drop out of 100 mph cruise (in those conditions, it converges to an average in well under a minute). My car consistently returns 20-21 mpg at 100 mph.
Using the same technique at other speeds, I've found that my car gets 28-29 mpg at 70 mph, and ~40 mpg at 40 mph (all in top gear). With this information (and approximations to my car's mbutt, aero properties, and rolling resistance), it's easy enough to estimate engine efficiency at each of these cruising speeds. The results:
40 mph, 9 hp, 40 mpg, 1.0 gal-hr, 0.66 (lb-hr)-hp 70 mph, 27 hp, 28 mpg, 2.5 gal-hr, 0.56 (lb-hr)-hp 100 mph, 62 hp, 20 mpg, 5.0 gal-hr, 0.48 (lb-hr)-hp
The last number in each row is a common measure of engine fuel efficiency, the brake specific fuel consumption (BSFC), expressed as fuel mbutt flow rate divided by output power. Lower is better, for BSFC. For gasoline engines, minimum part-throttle BSFC tends to be about 0.38 lb-hr-hp (more or slightly less).
Anyway, you can see that the engine efficiency is increasing (lower BSFC) even as the fuel economy is decreasing.
That's how Otto-cycle engines typically behave in pbuttenger vehicles, and that's why you *cannot* predict the rpm for maximum vehicle fuel economy based on the rpm (and load) of maximum engine efficiency. -- Chuck Tomlinson
