does shifting your car into neutral at a stop light save gas?

No more than you can tell the difference.

Yes, if you get your foot off the pedal on the right.

It’s not always a good idea, though — like of you want to be in control of your car, and certainly not on a long downhill — you might not be able to get back into gear, and you might, therefore, go ‘way too fast.

At a light, once you’re stopped and know that the guy behind you is stopping, it is a good idea to get out of gear (with a stick shift), saving wear on the clutch.

Once i see it is about to turn red i shift into neutral. Will you now get 10mpg more then before, NO. But every little bit helps.

not enough to be noticable

not really, because cars will free roll when they are not pulling a load. while you are at a stop light the car will actually use more gas as putting it in nuetral will free up the engine allowing it to idle higher. the only way to truly save gas to not try to get from o to sixty in one blck. try not pressing the gas as hard.

No to all three questions. That’s because you’re idling a little higher, than you will do in gear when the engine is working against a transmission than when you’re in neutral.

By shifting into neutral while descending hills, you are giving up precious engine braking control and wear will increase on the brakes which are far more expensive than the few pennies you’ll save on gas. The same goes for shifting into neutral when approaching a light or stop sign.

In addition, you are also increasing wear on the transmission which also increases maintenance and repair bills more than the savings in fuel.

No, it doesn’t. Your engine will be either idling with a load or
idling faster without a load.
Back in the ’70s gas shortage the ad coucil said that if you
are sure you will be waiting for more than a minute, you can
save gas by turning off your engine (at a stop light.)
Neutral going downhill will save you money only if the hill is
steep enough to maintain your speed.
Here’s what I do to gain 2 mpg on my 5.9L Pickup truck:
Slow and steady acceleration (traffic permitting), drive at a
speed just above (auto) shift to overdrive (or lock up), coast
as far as possible and even coast in neutral to a stop if
traffic permits. I use gravity to help accelerate going downhill
and I let my speed bleed off slowly going uphill. I drive a little
slower into a head wind and a little faster with a tail wind. A
direct cross wind counts as a head wind while a slight,
quartering tail wind is the same as no wind. Your tires
generate a little friction as they hold the road in a cross wind
thats why I count it as a head wind.