well, the last thing in a crash to do is put it in neutral...sounds like his crash caused a problem in the electronics, that allowed the engine to go full tilt...it shouldv'e rev limited itself, and certainly died once ignition was turned off. But, an air bag deployment will knock the crap out of you, and for a few minutes you may not think too straight...when involved in a serious crash, just hang on, apply brakes, once stopped turn key off...and try to get out once you access damage to yourself. Cars very seldom ever catch on fire..that's hollywood stuff, but someone else may crash into you again...so try to clear the scene to a safe place...call 911 once you are safe...