Driving in neutral

My 18-year-old daughter thinks it’s a good idea to cruise down a mountain in neutral. She thinks it’s safe and she’s saving gas.

I think she’s asking for trouble!

Not a good idea.

When she does this, there is no braking from the engine. This can result in overheating of the brakes which can result in brake fade. When this happens, you have no brakes. Besides, it’s against the law in most states to put your vehicle in neutral while in motion on a public road.


She is overloading the brakes which could lead to overheating, fade, and loss of speed control. Usually by the time speed control is lost it is too late to get into a useable gear to use engine compression for braking.

The prudent way to descend is to stay in a gear that allows the engine to provide most of the speed control and use the brakes to reduce the speed if it gets too high or to slow for a curve. The brakes should not need to be applied more than 30% of the time.

But, teaching prudence is a long and arduous process.

Assuming that she is driving something new enough to have fuel injection (say 1995 or later), then cruising down hill in gear will not use any more gas than doing so in neutral, in fact it might even use more fuel idling because modern fuel injection can completely cut off the fuel under some cruising down hill situations. As for safe, that sort of depends on circumstances, but in general it’s not safe because you may need to accelerate to avoid an accident, yes even going down hill. Finally, it is illegal to coast in neutral in many states, though obviously you are unlikely to be caught it might add another ticket to the charges if an accident were to occur and the car was found to be in neutral.

Overheating the brakes is another good point made by Researcher. That’s a dangerous thing to do. Overheated brakes can be very bad.

Poor economics and depending on the situation it could be dangerous.

We do extensive mountain driving and yes, you should keep the car in gear, but better yet, use a lower gear to help the brakes. On a 4 speed automatic we get out of overdrive both going up and going down a mountain. With a heavily loaded vehicle, you could lose your brakes going down in neutral. Once when towing a small camper, I could smell the brakes on a long downhill stretch. Fuel consumption is a non-issue here, nor is engine wear.