California Motor Vehicle Code 21710
Coasting Downhill Prohibited
California vehicle code 21710 states that it is illegal to coast your car when traveling downhill.
This law may seem dumb at first, but there are good reasons for keeping your car in gear while going down a hill:
- Better control of the vehicle. If you are coasting and something runs out in front of you, you have less control over your vehicle when it is not in gear. Gravity may not be your friend if you accidentally overcorrect to avoid a deer or a pothole.
- Engine could die in neutral. No matter how great you may think your car is, it can stop running unexpectedly. Driving at high altitudes is hard on the motor, and a car in neutral will sometimes die on you while you're coasting down hills, especially if it's a long hill.
- Brakes burn up faster on downgrades. If you're car is in neutral, it will naturally speed up going downhill. This requires you to apply more pressure on the brakes to keep it at a reasonable speed. The extra pressure on the brake pads will cause them to heat up and burn away faster. It is possible to lose your braking abilities if it is an exceptionally long hill.
- Coasting will not save gas. Once you are at the bottom of the hill, you will have to put the car back into a driving gear. The extra gas used to do this, makes up for the little bit you may have just saved while in neutral. It evens out in the end, and does not save you any gas mileage.
- Removal of feet from pedals. Many people take their feet away from the pedals while coasting. They take this time to relax and take a break from the driving strain on their ankles. If your feet are not on the pedals, you have no way to avoid sudden and unexpected road hazards.
If those reasons are not enough to convince you to keep your car in gear at all times, there are always fines and penalties that can convince you. You could pay fines and court costs up to $200 for your first offense. If you are a repeat offender, you could pay around $1000 after all penalties and fees have been assessed.
