Which is better for MPG in a manual car when driving,
You're going down a hill and don't require any gas:

A) You leave it in gear, or

B) You put it into neutral.

I have read that the injectors still send gas to the car when you are in neutal like in B. Also I have heard that if you leave it in gear, as in A, the fuel gets cut off till you hit the gas again.

I guess whichever is better would apply in all situations requiring you to slow down?

Well if the injectors shut off then the engine will shut off. So whadda think?



Tinkles

2003 Cavalier 1SV
Bagged and Blown

The main impetus behind the blanket introduction of fuel-injection in the late '70s and early '80s was not performance driven, but emission control driven. Carburated engines supplied fuel at all times, including deceleration when high NOx levels normally were generated. Electronic fuel injection allowed this to be dramatically cut because the fuel could be cut off completely on deceleration. (This doesn't mean idling, but slowing down in gear with the foot off the throttle.) The common thinking for generations was that some reduction in fuel consumption could be realized by coasting in a car with a carburated engine (though it is/was illegal to "coast" nearly everywhere). But, that went away with fuel injection.

leave it in gear, DCFO helps out alot with fuel mileage



1989 Turbo Trans Am #82, 2007 Cobalt SS G85

I pull it out of gear if its carbed or fuel injection. Whichever gives me less RPMs and less drag.

It's better to go downhill in gear... just think of the worst case scenario - if you go in neutral, and the car stalls... there goes your power assist brakes and steering. Not a pretty picture!!

And it will save you more fuel that way... the RPMs may be higher but you're not using fuel...

Tinkles wrote:Well if the injectors shut off then the engine will shut off. So whadda think?

As said above, Deceleration Fuel Cut-Off. Look it up.



87 Firebird
All stock...........lol.

Gas prices went down, leave it in gear.



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