Quote:
|
Originally Posted by beef_bourito
it will waste gas
when you're in gear and coasting to a stop (foot off the gas) the engine doesn't need to inject fuel. if you stick it in neutral it has to inject enough fuel to stay at idle. so in gear = no fuel injected, neutral = a bit of fuel injected. either way you won't be saving or wasting alot of fuel but if you've got an automatic you'll be wearing out the tranny alot more by switching in and out of neutral.
|
Agreed, mostly. In gear and coasting you still use fuel, just not as much. If you have access to a scan tool with datastream capability, watch the injector pulse width under all conditions. On my car, I use about 1/2 the fuel leaving it in gear and coasting as opposed to shifting to neutral. Your dad was right... back in carbureted days, but it's not true with fuel injected vehicles. Here in Iowa it's illegal to coast in neutral... but I don't know how they could possibly inforce that.
If you have a manual transmission, you can put it in 5th gear and turn the ignition switch to "unlock" and save quite a bit of gas if you drive down a 3/4 mile hill every day. That way you still have power steering and vacuum to refill the brake booster.
About the idle RPM in gear and in neutral... fuel used is very close to the same. Even though the RPM is higher in neutral, the engine load is less. I would expect fuel used to be nearly identical.