Correct me if I'm wrong...

[KARR]

Greetings!

On a forum about cars it's in discussion if driving in neutral will get 0 L/100 km or "infinite" MPG. It's been said that when a gear is selected mecanical energy from the wheels will keep the engine running on a steep furface, without using a single drop of fuel...

I'm not getting crazy am I? This is not true, right...??

[SVOboy]

It is indeed true. The engine becomes an air pump.

[MetroMPG]

Modern cars with computer controlled fuel injection will stop feeding fuel to the engine when the throttle is released above a certain RPM (usually above 1500).

[KARR]

But how can the engine be running without fuel being injected?

[SVOboy]

It's an air pump powered by the wheels. Normally the engine causes the wheels to roll, at this point, the wheels rolling is causing the engine to rotate.

[trebuchet03]

Agreeing with those that have spoken thus far If it did put fuel in there, you wouldn't be able to engine brake as you do now
------
Keep in mind that the energy necessary to keep the engine spinning is coming from the momentum your car has -- as SVO said, that momentum is being transfered through the wheels, transmission, etc. and into your engine.
-----
Driving in Neutral, however, will consume however much fuel needed to idle the engine

[KARR]

To all of you, thanks a lot!

[MetroMPG]

Important to note this applies to manual transmissions. I'm not sure it applies to automatic transmissions when the torque converter is unlocked.

[omgwtfbyobbq]

Same except the fluid coupling means more energy is lost via the trans.

[rh77]

By the way, welcome to GasSavers...

Nice car! This year, we get the Astra as a "Saturn Astra", but without the diesel option.

I think you may be our first Portuguese member, so a special welcome is in order!

RH77