Is it more efficient (in a manual) to put it neutral or keep it in first while at a stop light. I heard that most fuel injected cars the engine uses more gas in neutral than first. Was I misinformed? Any other insights?

 

I'm pretty sure it's a bad idea to hold the clutch in while waiting for a green light. Gas is ultimately cheaper than a new clutch.

 

You were misinformed. There is no difference in fuel consumption with either 1. the clutch engaged and the engine idling in neutral, or 2. the clutch disengaged and the engine idling with the trans in 1st. gear. You obviously burn fuel any time the engine is running, and it is equally obvious that you burn more fuel in all conditions where the engine is under load (moving the car or just being revved up with the gas pedal).

 

Does the same thing go for a AT?

 

ATs don't have to worry about a clutch o.O

 

you should just leave the stick in manual when you're stopped in case someone rear ends you. then you won't jump an extra however many feet and get smashed up in the intersection (hypothetically). i think it mentions this in the DMV handbook.

 

No they dont, but im not talking about a clutch..You can put a AT in neutral at stops too

 

But it's wholly unnecessary though

 

It will wear prematurely on your throwout bearing if you sit at stoplights with the clutch suppressed. It's generally considered better "stick shift" form to put it in neutral when stopped.

 

I agree with fedup put your stick in neutral at a stops = less wear on the T.O. bearing. as for us auto freaks just keep it in D and forgettaboutit.

 

You will burn less fuel if the AT is left in Neutral while idling, but it is safer to leave it in gear. The AT always consumes more fuel at idle than MT because the AT is mainly a hydraulic pump. Even in N, the pump imposes a drag on the engine.

 

It all depends on the RPM.

If you're at 750 RPMS in neutral, and 700 RPMS in 1st gear, you will use more gas in neutral.

If you're at 800 RPMS in 1st gear, and 700 RPMS in neutral, you will use more gas in 1st gear. Get it? It all depends on the car and your idle settings (if you've tinkered with them)

 

You forget that when in gear idling at a stop, there is always a drag on the engine because it is turning the torque converter. It always requires more fuel to overcome the drag of the torque converter at any rpm. The higher the rpm when in gear, the more fuel is consumed.

 

Not really it actually saves fuel

 

OK, I'll give you that, good point. Although I don't know how much of a difference it would make, but who knows.

 

Sort of like crazy old theologians arguing about how many angels can dance on the head of a pin, but thanks for seeing the point!

 

HAHAH! Thats funny because I had a Philosophy proffesor in college who said everytime she sneezed it was because angels went crawling up inside her nose.

 

ATs you are "supposed" to set it to Neutral even though 95% people do not. Idling at D is not really neutral. It's still spinning the torque converter which is connected to the wheels. So the engine is fighting a tiny amount of resistance.

When in N, your engine is idling with zero resistance.

 

You'll put more wear on your throwout bearing by engaging and disengaging your clutch, than holding it disengaged.


On the original topic - with the clutch engaged and the transmission in neutral, there might be a VERY VERY VERY slight bit more drag on the engine, since the input shaft of the transmission would be spinning, whereas having the clutch disengaged would not be spinning anything past the flywheel.

 

Srry gotta call you out on this, in my dads chevy blazer AT when you put it into neutral, the rpms go up a little bit. When in D its the brakes holding the car back, not the engine