I can't agree more with the previous comments!!
I wouldn't let the rear suspension of the 560 scare you off. Granted the shocks are pricey-- think I paid $900/pr
installed. But the spheres etc. aren't expensive and it is a DIY job. I'm thinking about doing mine this summer, but the car doesn't sag and the ride isn't harsh, so maybe there's no need yet.
MPG *is* an issue -- if I drove a lot, the 560 would not be for me. Perhaps a 300SDL. Either one (and the 420), you can't go wrong!