Quote:
Originally Posted by RhoXS
I completely agree. A higher rate of acceleration will burn more gas for the same change in speed than a lower acceleration rate. Slowly accelerating in as high gear (low engine rpm) as possible will give the best fuel economy. Petal to the metal acceleration makes Exxon-Mobile stockholders smile.
Back in the 50s and 60s there used to be a yearly long distant economy run that was always a feature article in Popular Mechanics. I think it was called the "Mobile Economy Run". They would take, if I remember correctly, a stock automobile and drive it across country and achieve some truly phenomenal average mpg numbers, much greater than anything normally achieved. I remember reading how they did it. They used very well practiced and disciplined drivers that held their entire bodies and accelerator foot extremely still. I read an article by one driver that even stated talking would reduce his economy numbers. If they slowed going up a hill they did not compensate by giving more gas. They anticipated stopping and used the brakes as little as possible, kept all the windows up for the least wind resistance, accelerated as slow as they reasonably could, etc. So, yes, using cruise control would not do as well here because the cruise control would add fuel and accelerate to maintain the preset speed.
Of course, a "however" is now coming with respect to the cruise control. However, if you carefully watch the speed of the average driver without cruise control, you will notice the speed varies quite a bit over a band of a few mph. This constant speeding up (accelerating) and slowing down is noticeably less fuel efficient than the constant speed maintained by a good cruise control. So, unless you want to drive ridged still, not talk to your passenger (that might be a good thing), and have practiced maintaining complete control over your accelerator foot, cruise control will allow you to use less gas.
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I'm not sure I agree. Yes faster acceleration requires a larger force from the engine but it requires it for less time. Everything is a compromise. Lowest possible engine speed is not the most efficient setting possible.
With engine speed you are balancing the inertia effects of the engine parts accelerating,the piston friction, and combustion efficiency with the heat lost through the cylinder walls. To wager a guess, I would imagine that the most efficient RPM for your engine to operate is slightly higher than what you might expect. The designers also had to balance noise and engine lifespan into the equation as well.
