• There is a short. Electricity in a car travels through all parts of the vehicle (well, the metal bits, anyway). The entire car is attached to the negative terminal of the battery, so basically, to get power you only need to connect your device to the positive side. One wire, no fuss. Unfortunately this also means that if that one wire gets crunched and touches metal, your battery drains away and nothing works. Note that none of what I have just said may be applicable for some new-fangled plastic car :)

My father was a heavy-duty mechanic.

Kickstart