I think for the price you will be paying for a CLS55 or an E55 you would be better off getting the new M5. It would be cheaper, it performs better than both cars, and overall I think is one of the most solid sedans out there, not to mention you cant argue with the performance (0-60 in 4.5seconds). But thats just my

and I'm much more performance oriented than comfort, but I would definitely say if you are shopping around in those leagues dont make a decision until you test drive the new M5.
