this was debated before, but no final conclusion.

when in gear and not giving gas are you using gas? and if so, would coasting in neutral save gas?

 

coasting in neutral = saves gas (MT/AT)
slowing down while in gear = saves gas (MT)
slowing down while in gear = uses gas (AT)

that's my story, i'm stickin' to it

 

 

 

Coasting in neutral uses gas.

Anytime you are in gear and not using the throttle, you are not using any gas. The ONLY exception to this is if you are in gear and the engine speed is below the idle speed. The engine will always inject just enough fuel to maintain idle.

If you are moving, it is always safer to be in gear. You can use the engine to brake, you can accelerate at will. Being stuck out of gear can leave you stranded in a dangerous situation.

 

It's not worth the risk

 

+1 for slim. Any car made since like the 80's will not be injecting fuel during decel in gear. The injectors are shut off and the engine basically becomes an air pump. Supposedly (and I tend to believe this), the SRT4 cal injects some fuel during decel to get the poppiness out of the exhaust.

Just a bit of trivia.

 

For those of you who like to "stick to that story", you better find another story. The S2000, when in gear and foot off the gas, clutch engaged, decelerating, rpm above idle speed, will cycle the injectors OFF. Therefore, NO gas is being used. If you throw it into neutral and coast (bad driving skill, BTW), you ARE using fuel to maintain idle.

 

so going down a massive hill at 5k rpm 60 mph, no throttle uses no gas?

 

totally true. injectors are off if there is no throttle and the engine speed is above idle. it just acts as a big air pump at that point.