downhill on gear fuel consumption

[Scarsman]

I agree with Hellz, if all fuel was cut off, then the engine will stop. To prove this, try coasting down hill and turn off the key. Your tach will drop to zero and the engine is dead. If "gravity" and the tranny spinning were keeping the motor turning, then it would keep turning when the key is turned off, but it wont.

Now if you have a manual transmission, then it is a different story. Now you have a mechanical link between the motor and tranny, and as long as the wheels are turning the tranny, then the engine will also be turning. Not so with an auto. Other wise you would be able to roll start an auto like you can with a manual. But you can't. Roll a dead auto down hill and put it in drive and nothing will happen.

[wingn69]

If your worried about gas usage you shouldn't be driving any of the cars your currently own buy a hybred smart car or get a skate board they use no gas going down hill.