You should get a Trabi!
Ok, ok... I'm kidding.
Will you have a garage? You know most Germans park their cars on the street. You will also need ~1,500 euros to get a German driver's license.
Also... what ever car you do end up getting... you will be paying tax and insurance on it. The tax for a small 1.0liter micro car is about 150 euros per year. For a 1M its around 800 euros. I think for a V8 M3, its over 1K. So take that into account.
Fuel is expensive over here. Its around $9 per gallon. And with no speed limits, its hard to conserve fuel. IF you get a diesel, the fuel does costs less, but the yearly tax is higher - so it all kind of balances out. Right now a liter of diesel costs 1.30. Super will run you about 1.50. But in the summer time(driving months) its more around 1.50 and 1.75(respectively).
Oil is very expensive too. Most oil sells for 10 to 35 euros PER liter! An oil change at any dealer will run around 300 to 400 euros(for four of five liters of oil!). Most Germans only change their oil once per year.
You can look on
www.mobile.de for German cars and see the prices. Just select ENGLISH tab, on the top right corner. Also make sure only to search in Germany.
I would say look at a two year old car, that is a certified used car. A lot of the cars for sale have been in accidents. Its hard to tell. Also... many have their speedo's rolled back. Look at the tell tell signs like worn steering wheels and seat belts and driver's seat wear. I think three out of five cars have been "messed" with. Also having a car checked out by TUV or DEKRA is a good idea. You'll likely pay 100+ euros for a ppi, but its worth it.
Also join ADAC, the German car club. Pay for the extra PLUS membership. It will save your a$$ one day.
Hope this help you out. Maybe rent a car for a month until you decide what you want to drive.
Dackel