will driving in neutral in four speed automatic small sedan saves gas ?

i dont think you can drive in neutral.

If you put your car into nuetral when coasting and avoid “engine braking” by leaving it in gear, you will reduce the average rpms of the engine when it is not producing power.

When the engine is not prodeucing power it is just waisting fuel keeping itself turning, so the slower it turns the less fuel it will waste.

If you leave your car in nuetral when you are stopped, the engine will not burn extra fuel to fight the hydraulic friction in the torque converter, Though the engine rpms do not change when you are not moving and are in park or nuetral. The engine must produce slightly more power when you are in gear and stopped than it has to when you are in nuetral and stopped in order to maintain idle rpm

I sometimes do this, based on this theory, and the fact that it has trivially small efect on engine life as well.

Using neutral can be very dangerous,
for best mileage drive with traffic, keep up with the slow lane and don’t cause a blockage. you’ll get good mileage following traffic. the biggest thing you can do is your driving style, you get twice the mileage slowing down and triple going down hill, so the sooner you let off the gas the better you will do. anticipate stop signs and lights, left off the gas as soon as you can..
Always use your od, if you don’t have one, put on 2 size larger tires on the drive wheels and remember to figure a correction for mileage. you can check it against a gps to find it..
it really helps if you have a car with a mileage computer so you can watch it…