So, I heard Click & Clack tell some poor woman to have her husband drive naked to avoid the static shock he gets from her car. Have these two never heard or seen the key trick? Just take a nice metal key, like a house key or such, in your hand and touch that to the door handle first. The spark jumps to/from the metal key, without the person feeling any pain. The pain is from the arc, and if the arc hits the key the person does not feel it.
Also wanted to add that waiting a few seconds before getting out of the car helps. The electricity discharges through the tires more slowly with modern (high silica content) tires. The man probably habitually gets out of the car immediately, and the woman probably takes her time.
Right, soggydoggy! Except when she’s racing you to the bathroom!! 
If you reach above you and touch the doorframe/top of the car as you exit, you may hear a faint crackle and feel an equally faint sensation, but nothing approaching a shock.
Also helpful is using your car key to take the shock. Grab your keys (skin touching metal part of the key) and touch the key to the car after getting out. The electricity arcs from the car to the key & you don’t feel the zap.
Yes. I learned this technique many years ago, after continually getting shocked when exiting the vehicle. Before exiting, (as flat5er suggests) I place a finger or hand on the door or roof (some exterior metal part of the car) to ground myself as I slide across the cloth seats and exit the vehicle - no shock. I’ve been doing it for so long now it is second nature as I exit the vehicle.
I do the same as the previous poster, and it’s also become second nature for me. I keep a hand on the door frame as I step out of the car. The discharge, if any, will be between shoe and floor and you won’t feel it. Once a foot has touched the ground you don’t need that hand on the door any more.
The problem is caused by static charge buildup when you slide across the seat. We have success spraying anti-static spray on the seats once a month. The amount of charge build-up depends on the seat cover material and your clothing. If you wear denim, purchase some denim seat covers and charge cannot build up. For a discussion of charge build-up between different materials, see http://en.wikipedia.org/wiki/Triboelectric_effect
and
http://www.school-for-champions.com/science/static_materials.htm
The discharge is actually through your hand to the car body. The static comes from rubbing on the seat as you exit. Anti-static spray helps this a lot, as mentioned elsewhere. Holding on to the metallic body (or anything metallic connected to the car body or frame as you exit does a continuous discharge to the car frame which is not painful because there’s no big spark jump across a gap.
No wool or polyester.