I used a Yak-rack on my old 123 sedan for years with no problems; I imagine it would fit your 123 coupe just fine. As I recall, there were two possible ways to mount on that car. You could go with the rain gutter mounts, or use the Q-towers (which sit atop the roof on rubber feet) with the appropriate clips to grab under the rain gutter and hold the whole affair in place. I had the latter setup, and it worked just fine. That said, I'd recommend the rain gutter mount - nothing touches the cars' paint.