No one seems to be answering the question correctly, so here goes: On a long descent, excessive use of the brakes can cause them to overheat and "fade", meanin

No one seems to be answering the question correctly, so here goes: On a long descent, excessive use of the brakes can cause them to overheat and "fade", meaning that you will not be able to stop the vehicle at the bottom of the hill. This can be caused by loss of friction from overheated brake pad material and rotors, or by the actual brake fluid itself boiling out of the master cylinder and becoming compressible. This is not nearly as prevalent as it used to be, now that vented disc brakes are standard on most modern vehicles. See http://en.wikipedia.org/wiki/Brake_fade http://en.wikipedia.org/wiki/Brake_fade Another reason is that fuel injection is cut completely in modern fuel-injected vehicles under compression braking, meaning you will get better gas mileage if you engine brake than if you idle down the hill.