I also like the idea of a fire detection and supression system integrated into the engine compartment, gas tank area, and trunk of cars. I think a simple device would cost less then $50 each to manufacture and install, (fire extinguisher attached to a smoke detector) and could save lives and prevent damage in case of a fire after a major accident.
Actually, another idea I just thought of was having a "neutralizing bomb" placed inside a vehicle's gas tank(s). The idea is that in a severe enough accident, the "bomb" will activate or rupture, releasing a fire-retardant chemical into the fuel tank of said vehicle.
