IF I put my gear on neutral, does that save gas?

only if your RPM’s significantly drop while doing so.

not enough for you to really notice

If you coast or are going down hill yes.
Red light no, if you have a tachometer check it at a red light.
im assuming you have an automatic transmission.

Not enough to make it worth the effort. If you’re going to be stopped for more than 60 seconds, you could put it in park and shut it off. That’s more something you’d do at train crossing with a long freight train, not at the normal light.

Probably only if you are doing the “hyper miling” thing.
In that sense you would need to be in motion and go into neutral and coasting to say, a stop sign.
Do a Google search on “Hyper miling” to increase fuel economy.

No, your torque converter actually has the car in neutral until you press on the gas and the converter spins and pushes the fluid in the transmission to engage the clutches, putting it in neutral is a waste of time, same goes for a manual, if you have the pedal pushed in the transmission is disengaged from the engine.

nope! it won,t save a bit. after all your engine is still running.

If you are stopped at a red light then the gearing doesn’t matter at all. Like the previous answer; the car is still running at the same rpm requiring the same fuel consumption. While coasting down a hill, you will save a very small amount shifting into neutral; but know that if you are planning on keeping the car for a few years, this will put more stress on your transmission and won’t be worth the few dollars saved when having to have work done on the tranny.