This whole thing seems really weird. The driver can’t possibly be getting shocked by the car’s electrical system. It would have nothing to do with the car being hybrid. Electrostatic charge build up would have to be what is going on. If this is the case, then both driver and passenger should feel it as well. If any passenger touches a metal part of the car it should balance their electric potential with that of the car. This will prevent future shocks when touching metal parts of the car, but then the passengers’ hair should start to stand up on their heads as the electrostatic charge builds up. Everything that has electrical charge will start to repel from everything else with the same polarity charge. Hair on your legs will start to repel from your body as the charge starts to get really strong.
You should build an electroscope to see if static charge is building up. Here are directions: Detection of Static Electricity by Ron Kurtus - Physics Lessons: School for Champions
Use the electroscope while you are driving.
The electrostatic discharge car accessory is a good idea. I didn’t know such a product existed! Since it does this must be a known issue.
I get shocked in my car but it is because I drag by butt over the seat as I get out and charge up my body before I reach to close the door which is when I get shocked when I touch it. It’s not because my whole car became charged.