Whenever you touch the car something goes off under the hood...it sounds like a little electric motor. Maybe it's the electric water pump? I think it's even gone off before when I just bumped or touched the car....

 

It's not everytime you touch the car ... However the smae thing will happen when you open a door, the bonnet or trunk.

 

Does anybody know what that humming/buzzing sound is?

 

Its the fuel pump priming. Just called my dealer and they told me they get that question all the time.