Quote Originally Posted by blutopless2 View Post
not quite... still need fuel to keep the motor running.
not not quite, actually - Transporter is 100% correct - there is actually no fuel being injected when on the over-run ie the momentum of the car is keeping the engine turning over. So when the MFD says 0.0 l/100km it is exactly that. The injectors will start injecting fuel again when the engine is approaching idle speed to stop it stalling.

So if you time your run right you can back off as you approach a red light, and you are using no fuel whatsoever on the run up to the light. This helps fuel economy.

There are some that debate that if you lift off too soon you have to your foot on the accelerator again to stop slowing down too soon and this uses more fuel than putting your car into neutral and coasting in with the engine idling, and the even more extreme will switch their engine off (but I think that is crazy stuff, and totally inappropriate for driving on public roads ).