With cloth seats and low humidity, it's a problem. It seems to be caused when you slide across the seat to get out of the car. It causes a static electricity charge to be generated. There is much written on it if you do a google search. I solved it by only buying cars with leather seats then it's no problem.
Yep! I hate that when I get zapped. My old car had cloth seats and floormats. What I did was mix some fabric softener with water in a small spray bottle and spray the seats and floor mats. This works great for eliminating the static electricity! I spray about every 3 weeks or so. Since part of my seats are leather in my new bu, I use a damp cloth that was dipped in solution of the fabric softener to wipe around the leather, and on my floormats. You can also use a fabric dryer sheet that is wetted down too, but doesn't work as well in my opinion.
I spray my furniture and carpet areas in my house in the winter time too, with the fabric softner and water solution to prevent getting zapped.
I just thought I would add that I use unscented fabric softner because I don't like the scented ones.