I've also wondered this every time they play a news bit about people stomping on the brakes and flying off a cliff.
Answer: Darwinism.
Actually, Car and Driver (most recent issue) tested a Camry, along with a couple of other cars, one a highly powered Mustang, and in all cases brakes > engine. In other words, brakes can easily overpower an engine stuck at high speed revs. The Camry stopped just a bit longer than it would have taken had the engine not been full on. The Mustang was quite a bit harder to stop, but stop it did.
Obviously, in all cases stopping distances are increased if you're fighting the engine, but still. Many car makers, (Audi for one) have an automatic engine rev-down ability when brakes are applied, that is, no matter what the gas pedal is doing, the engine will drop to idle speed if brakes are being applied. Toyota / Lexus don't have this, but will soon.
