S6devil

iTrader: (10)

Im sure this was brought up 47 times before, but I cannot find a single thread in the recent past about this.
Anyway, the real reason im posting is because in the current edition of Car-n-Driver, they actually test the difference between leaving the car in gear or throwing into neutral when coasting to a red-light, or to a stop.

The aspect of being in gear 'in case of a sudden need to speed-up again' aside, just in terms of fuel economy, it is better to leave the car in gear, and let the drive-train pull the engine. it is mainly because of special ECU programming in most new cars which actually shuts off the fuel pump when it detects 'idle coasting'... no matter what your rpm is (since u r in gear), it is not gasoline that is reacting and forcing the pistons up and down, rather the engine is simply turning because of the wheels and drivetrain which are already in motion. the throttle body and fuel pump are closed

Billy@EnglishRacing

iTrader: (18)

really it all comes down to your driving style

baylorar

iTrader: (8)

i do both. i can't imagine you'd actually be able to notice the change in gas mileage given they way we drive :P

Craig King

iTrader: (11)

I like to turn my car off, take the keys out, then try to stop without power assist brakes.

S6devil

iTrader: (10)

i gotta agree. whether we argue about here, whether a magazine tests it out... its all the same. no matter how i try to change my driving style, or even driving routine every day, i still get 11-12mpg int he city, and like 19-20 on hwy (with a 6sp!!). cannot do a thing about it!

bluebanana23

iTrader: (26)

my friend with an s2k leaves it in gear claims to get 20 extra miles to the tank when compared to coasting. I tried it on 2 tanks and barely noticed a difference.

Kracka

iTrader: (49)

Leave it in gear. Save a bit of gas and be prepared to react more quickly if the situation suddenly changes.

prind0

This.

I'll usually stay in gear if I'm coming up to a red light that might change to green soon, and I'll put it in neutral if I'm coming up to a stop sign where I have to make a complete stop.

Spish

iTrader: (8)

I stay in gear until rpms drop to about 2k, then just pull out of gear, no clutch.

Oki Panoki

iTrader: (8)

you get better gas mileage with it in gear. there was a thread about this before and tuner/mechanics/w/e said that the injectors feed little or no fuel (less than idle, if any) if the engine is experiencing negative load. i believe them. if you have a wide band also it will go all the way to its leanest reading so...

Oki Panoki

iTrader: (8)

who makes complete stops

S6devil

iTrader: (10)

yes thats what i wrote in the original Post above. the magazine did a test (only to see affect on fuel economy) and their results showed that leaving in gear is better for mpg.
also in the same article, an industry engineer said that most new vehicles have special cutoffs that momentarily turn off the fuel pump when the car is in gear but there is no engine load (i.e. coasting).

this whole thread is an FYI...

mini_evo

iTrader: (3)

Stay out of boost, keep the RPM's under 3000 as much as possible, and as for coasting, it only really works if you are going down a hill. On flat ground it doesnt help since our cars have so much drivetrain resistance.

baylorar

iTrader: (8)

same here - getting crappy gas mileage is all a part of buying an evo

baylorar

iTrader: (8)

i'm such a newb lol - i pulled it out of gear like a month ago with no clutch (no throttle obviously) and i about sht. i didn't know you could do that