Does an automobile engine takes more gas while in Netral or in a gear with Breaks on?

Question

I travel alot and my car has a slightly large engine then a 4 cylinder. to use minimum amount of gas/petroleum, I shift my gear to neutral when standing still at a trafic light thinking It would save gas....

I look at the fact that electric motor takes more electricity when given load or perhaps too much load making it stop eventually...

I am not sure about a gasoline engine? does a gasoline engine spend more gas/ petroleum when it is running free or when it has been forced to stop the car from moving??

Answer 1

First, your question:
While stopped, leaving the transmission in gear and applying the brakes to force the torque converter to engage will use more gasoline than if the transmission is put into neutral or park. In neutral and park, the engine only has to supply enough gas to keep the motor turning, whereas with the transmission engaged, there is a constant force being applied to the transmission, and to the wheels, which must be counteracted by applying the brake. That extra force requires extra energy, which means more fuel going to each cylinder on every revolution in order for the engine to maintain its idle speed.

Now, to rebut a couple of the other answers:
Your car does not burn more fuel while idling than it does when you're driving. No matter how well designed your vehicle is, it is still subject to drag from the air it displaces. To maintain a particular speed, you have to give the engine enough gas to compensate for the drag. That's why you have to keep your foot on the pedal when you're on the highway. When you're not moving, there is no drag, so again - just enough gasoline to keep the motor spinning. A vehicle with good aerodynamics reduces, but does not eliminate, drag.

A commonly confused aspect of this is fuel efficiency as measured in miles per gallon (or kilometers per liter in the metric world.) When you're not moving, your miles per gallon measurement at that instant is exactly zero. From a travel point of view, it's all wasted fuel.

The question basically amounts to how to use the least amount of fuel possible when you're stopped for a red light. Obviously, shutting the motor off is the ideal, but unless you're driving a vehicle that was meant to be driven that way (such as most of the new hybrids, which do that automatically), the constant starting and stopping of the engine is going to have a bad effect on the starter motor and the battery, among other things. From a pragmatic standpoint, It will also take longer to start moving again.

Having eliminated (except for hybrids) the 'ideal' solution, the next best thing is to drop in into neutral.

I should point out that how much of a difference putting the car in neutral makes is going to depend largely on the vehicle, but in any case it probably won't be a huge gain in overall fuel efficiency, since you'll end up burning such a proportionately larger amount of fuel while you're actually underway.

Answer 2

In short, putting the car in neutral does not change how much gas you should burn at a stop light, the only reason it would is if the car shuts down any parts while it is idling, but when you turn the car on all the parts run and it doesnt matter what gear you are in when you are sitting at a red light other than pressing the gas, it will not make a difference.

But the car is able to use less gas while running due to Aerodynamics, and having the wheels rotate without having to press the gas because of inertia and momentum and not having to press down on the gas as much.

Answer 3

Your car will burn more fuel if it is idling. Running the car on the road will not burn more gas. Having it sit while running will.

Answer 4

yes when in gear it is doing more work, your brakes are holding it. It is puthing against the brakes. The computer in the car adds more fuel to compensate. http://www.gassavers.org/showthread.php?t=2510

Answer 5

You actually use less fuel when you're moving.