Seriously, me also have this problem especially when i get out of the car. You will notice me always carefully choose a spot to push the door close coz if i touch the metal part, there will be a electrostatic, a sort of sparkle..it's a bit painful mind you. Normally i will push the door window to close the car door. And also if i touch anything esp metal ie gate or grill...
What is the reason actually, anyone can give a good explanation..