does shifting into neutral really save any gas?

It might save you a pint of gas, but you are putting yourself at risk by coasting with your car or truck or whatever, it is very dangerous to do that. You do not have complete control of car. It is also hard on your brakes and it is against the law in many states. Watch out you don’t get caught.

If it is a modern car (fuel injected), no…

When I first got my license I did this all the time, but it actually does nothing for you if your car is fuel injected. Every time you let go of the gas it nearly shuts off the fuel and does the same thing as putting the car in neutral. A good example of this can be found in modern cars that calculate instant gas mileage. Every time you release the gas pedal, it kicks the mpg meter to its maximum.

Let me offer you a suggestion: Instead of coasting, allow the engine to slow the vehicle down. This will lower your brake usage and save you money over the long run.

No you don’t save gas, it takes less fuel to maintain speed than to gain speed. Every time you shift to neutral your car slows down rapidly. When you put it back in gear you give gas to to pick your speed back up.
In fact back in the 50′s when Plymouth did the coast to coast milage runs. They found that over a course of 100 miles they used 15% more fuel by doing this. And as the other person pointed out it’s not safe because of lost vehicle controle.

First of all, I am assuming you don’t mean doing this on a level road where you’d have to get back on the throttle to get back up to cruising speed. That violates one of the cardinal rules of high-mileage driving — Drive at a steady speed! Any fuel you save coasting in neutral is more than gobbled up when you have to accelerate back to cruising speed.

So lets assume you mean coasting downhill, or when you see that you will have to slow down or stop anyway.

There is a very good reason why coasting in neutral saves less fuel than just letting up completely on the throttle.

If you leave the transmission in neutral, you will still need a little gas to keep the engine idling while you coast. Leaving it in gear tells the computer to give you engine braking, so it cuts off fuel entirely, preventing exhaust emissions.

It’s a very small difference, but add it to the safety factor, and you are better off just letting up on the throttle.

No, you trade safety for fuel savings. It’s not worth it. Modern cars have anywhere between 5 and 8 speed automatic transmissions which anything after the fourth gear allows the engine to run at a lower rpm, especially larger engines that generate large amounts of torque or cylinder deactivation technology (8 cylinder engine using 4 cylinders).