These posts are helpful, I appreciate the input. I am going to borrow each car for a day and hopefully that will clarify whether an X and S550 or one of them with the 335i will get me off the vehicle treadmill. (admittedly, a pretty insignificant problem in the scheme of things) Still not sure about the statement the Mercedes makes.

Do you miss the 335 or is the fun itch cured when you can drive the X? I basically drive the 335i around town and 2.5 hour (one way) trips to daughter's college. Mostly at 80-85 mph on highway. The longer 8 hour trips would be through mountains to NFL games.

I guess the knees will be an issue with either car-and more frequent stops are inevitable.