Company Car (Frankfurt)

Part of my contract here in Frankfurt includes a company car, which I understand to be fairly standard in Germany. I do need a car here, but my tax obligation for the car is very large - more than what I pay for my car in the US. Obviously it's a much nicer car that what I drive in the US, but I don't know that I need something that nice. My question is - does anyone ever turn down the company car because the taxes are too high, and just find one on their own?