I had been pondering as to why my car occasionally zapped me or my wife as we got out of the car, I had assumed that I/she was discharging the car. I alway let her get out first so she would get the shock. Then the other day it came to me. I got out first and closed my door, no zap. She got out and "oh f*@!", she got zapped. I realised that we were not discharging the static build up on the car through ourselves but discharging static on ourselves through the car.
If you think about it, you are sat in your car with your best lilac nylon shirt on, sitting on a plastic seat, you feet in contact with either a rubber mat or rubber coated foot pedals with your hands holding a plastic steering wheel or gear knob. As you shift around in your seat, turn the steering wheel etc etc you build a great big static charge on yourself (someting like 10kV). You get out of the car, your shoes insulate you from the ground, you touch a metal part of your grounded car and whammo, you utter an expletive and kick the car.