It even happens with the leather. I have been dealing with this for years. Anytime the weather dips a few degrees, it tends to happen. the A4 seems to be worse than any other car I have owned. I do remember it happening a few times in my 90, but it seems to happen daily in the A4. The worse thing is that it does not hurt, but it scares the bejesus out of me, each time it happens.

I think it has a lot to do with not only your seat material but the amount of plastic around. My old car was a neon and it's cloth seats combined with massive plastic door panels could offer a hell of a shock, especially to those who weren't expecting it. I found the best way to deal with it is touch the metal on the bottome of the door frame after you open the door with your leg (unless you wear knee high sock or something). You still get a shock, but your leg is far less sensitive than your hands. The problem is worst in low humidity.