Funny you mentioned this. And no offense to you, but this is B.S. I was at the Z4 factory in South Carolina a couple weeks ago and chatted with one of their senior engineers about this since so many people have been saying it. Your statement is simply not true.VTECaddict wrote:if you're going downhill and your foot is off the gas, it doesnt matter if the engine is at 500 rpm or 5000rpm. it will not use a drop of fuel.
When you're going downhill and the RPM is at, say, 1100, the engine still uses as much gas (which, in all fariness, is minimal) as it does when the car's idling in neutral. For BMW's, the gas flow does not cut "down" (again, down, not "off") until the engine revs reach below 1500.