Spring wire straightening

the simple answer: Electricity always seeks the path of least resistance. The metal and mainly wire was that path, thus the energy went thought that. The slightly more complex answer: Strictly speaking : electricity will always seek all of its available paths and try to flow thought it but to make a successful path it needs to overcome the resistance of said path, the output of the car battery is not high enough to overcome the resistance of human body in that situation! but is enough for the metal-wire.