Are you trying to *invent* an agenda? Who suggested that you (or anyone else) shouldn't drive faster than 50 mph? I cruise at 75-80+ mph frequently, even though I have data to show that my car is more economical at lower speeds.
Actually Dave, the *age* of Garth's car is not the issue. The *design* of his car is the issue.
I doubt that his car delivers optimum mpg at ~65 mph in proper tune but in its current state, the likelihood of poor fuel mixtures and an energy-wasting transmission design may mean that his car peaks at a higher speed than a modern car with constant mixtures and energy-efficient transmissions.
If his engine is in poor enough tune, and his trans is "sloppy" enough, he *could* have an mpg peak near 65 mph.
But I *know* that *your* car does not deliver best economy anywhere near 78 mph. It *cannot* sustain 42 mpg at 78 mph on level ground in still air.
I don't think you're a liar, because you seem to believe what you're saying. You're simply *wrong*, but you don't know enough to realize it, and you'd rather wallow in ignorance than allow yourself to learn.
At what load? At what vehicle speed? If you don't know why engine load and vehicle speed matter, read (and understand) Todd Wbutton's long post, or continue to embrace ignorance and make a fool of yourself.
At 60% of peak power rpm in top gear, my car is running at ~125 mph, and 65%-70% of full-throttle torque (probably just short of power enrichment). IOW, my engine is operating very close to *maximum fuel efficiency* at 125 mph.
My car is EPA-rated at 18 city-24 mpg highway. If the engine is most fuel-efficient at 125 mph, as I (and your source du jour) think it is, what fuel economy (mpg) should I expect at 125 mph, Dave? Anyone?
BTW, why have you not tried to answer any of the questions I've asked you in this thread?
1. No expert believes that maximum vehicle fuel economy necessarily (or even occasionally, in modern cars) occurs at the engine's most efficient operating state (rpm and load). 2. There is no such thing as "the RPM of maximum fuel efficiency". Maximum engine fuel efficiency occurs at a combination of rpm *and load*.
3. The engine's most efficient load-rpm point is irrelevant to the vehicle's most economical cruising speed.
Keep your car. Learn from people who know a lot more than you do, Dave. Either that, or prepare to (continue to) prove yourself a fool. -- Chuck Tomlinson
