That tiny B on your gear selector could matter most when the road drops sharply ahead. While many drivers leave it untouched, this overlooked setting can help control your speed when a long descent puts extra strain on your brakes. Knowing when to use it starts with understanding what happens before your brakes face far too much sustained pres…

The B on an automatic gear selector generally stands for “Brake” or “Braking.” Found in many hybrids, some electric vehicles, and certain CVT-equipped cars, it provides additional slowing when you ease off the accelerator. Depending on the vehicle, that can involve regenerative braking, engine braking, or a combination of both. The result is extra speed control without relying entirely on the brake pedal—a useful advantage when gravity keeps pulling your car downhill.

On long, steep descents, this assistance can reduce the load on your conventional brakes and help limit overheating, which can weaken braking performance. But B is not a replacement for the brake pedal, nor is it automatically the best choice for fuel economy or battery charging. For ordinary flat-road and highway driving, D remains the usual setting. Check your owner’s manual for your model’s instructions, and use B where recommended to make demanding descents more manageable.