Actually the tires are your enemy when it comes to electricity because they keep the electricity from grounding properly. If a car is hit by lightening or has power wires fall on it you're safe on the inside because the negative (bad) electrons go outward along the body work and frame. This means that the car is acting like a battery and holding a charge until it is properly grounded. If the car is hit by lightening and you get out right afterwords you will be in for a major shock. If this ever happens to you make sure you ground the car some how before opening the door or wait a good period of time for the electrons to dissipate in the air.
It's been a while since I studied the properties of electricity but I believe I got all the major points.
RIP