All parts have to be TUV approved to pass the German MOT (iirc), which if the car has been maintained over here may not be the case. I may be hugely wrong on this, but it's worth checking.
Just had a quick look-TUV thing seems to relate mostly to compliance of headlights/tail lights when doing the registration inspection-doesn't sound too onerous considering the make of car, might be different if it was something exotic or RHD though!
All parts have to be TUV approved to pass the German MOT (iirc), which if the car has been maintained over here may not be the case. I may be hugely wrong on this, but it's worth checking.