It's been over 10 years since I left Germany, but the rules at that time were:
The military would pay to ship one vehicle over for free.
The military would pay to ship one vehicle back for free provided it had previously been in the United States.
This is a change from before when they would ship one vehicle regardless.
My recommendation: Don't ship your current car. Take one of several options:
Sell or store the car and get one there. Servicemen are always trying to sell cars cheap because they can't ship it back, or bought something new while there. You could also buy something there that you can't get here and run it while there. Sell it to someone else before leaving.
Take your car there and sell it before it quits. If it dies, or gets wrecked, disposal is a real pain with the German government.
The cars there may cost more to buy on the economy, but the selection can be very interesting.
Things to remember: Good insurance it essential - IMHO USAA is the only way to go overseas. Fast, good, cheap, and they know the local laws.
American cars overseas can be a bitch to get parts for. Minor wrecks will total an American car.
Cabriolets (Convertible or Drop Top in other words) are great to motor in the mountains. Do the British touring thing, put the top down and the windows and heater up.
Just some thoughts,