Emergency 8: Stuck Throttles and Sudden Acceleration
Thanks to things like loose floor mats and a poorly placed racecar throttle cable, I have experienced stuck throttles. If your engine starts racing away uncontrollably, you must stop it immediately. If the car started accelerating when you pushed the brake, release that pedal. If the engine stops screaming, you were actually pushing the throttle. Now try pushing the pedal to its left. If that doesn't stop the vehicle, slap the transmission into Neutral. Don't worry about inadvertently shifting into Reverse. Most modern vehicles will not allow you to do that without manipulating a button on the shift lever. And if you do manage to get to Reverse, the computer in the transmission of all modern vehicles will reject your request. As a very last resort, turn off the ignition.
While taking these actions, press the brake as hard as you can. In every well-maintained modern car, the brakes easily overpower the engine, even if the transmission downshifts a gear or two. If you're truly pushing the brake as hard as you can, the car will stop, even with the engine going full speed. However, the brakes can't beat the engine forever and people with physical problems may not be able to maintain adequate brake pressure, so select Neutral and turn off the ignition.
by Mac Demere, Contributor at edmunds.com