NOTE: I'm pretty sure this is an urban legend at this point. Oh well. In fact, read this for a good story (with a ring of truth) by someone who claims to basically be responsible for the legend.
The Arizona (U.S.) Highway Patrol came upon a pile of smoldering metal imbedded into the side of a cliff rising above the road, at the apex of a curve.
The wreckage resembled the site of an airplane crash, but it was a car. The type of car was unidentifiable at the scene.
The boys in the lab finally figured out what it was, and what had happened.
It seems that a guy had somehow got hold of a JATO unit, (Jet Assisted Take Off, actually a solid-fuel rocket) that is used to give heavy military transport planes an extra ``push'' for taking off from short airfields. He had driven his Chevy Impala out into the desert, and found a long, straight stretch of road. Then he attached the JATO unit to his car, jumped in, got up some speed, and fired off the JATO!!
Best as they could determine, he was doing somewhere between 250 and 300 mph (350-420kph) when he came to that curve....
The brakes were completely burned away, apparently from trying to slow the car.
NOTE: Solid-fuel rockets don't have an ``off''... once started, they burn at full thrust 'till the fuel is all gone.