[pooyab]

My wife and I are cross shopping the two obvious replacements for her C63S while we find a new owner for it. We managed to test drive both last weekend and had mixed feeling on each.

E63S:
We drove this car first and thought it was perfect (it was an Edition 1). Very nice interior, looked great in satin black, sounded fantastic and was quick. A lot of people seem to complain about ride quality but we had no issue with it. Coming from her lowered W205, M2 and Abarth, the stock E63 was smooth lol. Seemed like it was everything we always wanted the C63 to be. In my opinion the power of the C63 makes it feel too unbalanced to drive spiritedly. Really the main concern was the paint maintenance for me.

M5C:
The following day I found a M5C to test out. Oh man, the car sound so much better than the normal M5 and feels much quicker than I remember. We couldn't stop laughing during all the pulls we were doing, it almost made us think the E63 was slow in comparison. After some research I realized it's the way the M5 delivers power and other YouTube videos show the same. The transmission on the M5 was much smoother and a less eventful (pro or con?). The main disappointment for me was the steering feel, the M5C feels pretty numb. It goes where you point it but there's little to no feedback on where the wheels are, E63S wins this aspect.

So each car has its pros.
M5C: easier to mod, faster, exterior looks better (wife disagrees), iDrive (significantly better than command), better AWD system
E63S: better interior, better sound, better steering feel, will retain more value in coming years, has bucket seat option (requirement for us in AMGs)

Whatever we buy will get intakes, downpipes, and a tune, so I was interested in seeing which one can handle the ~650-700whp best (torque limited tune to 650wtq?). After continuing to read about each car, the F90 seems to be a bit more reliable than the F10 was and doesn't have the transmission handicap. The E63S on the other hand seems to have potential electrical bugs, transmission and diff failures, and even suspension leaks.

Hoping to get some insight from owners of one, or both, in terms of reliability and overall experience. We generally put about 12-15k miles a year on a car, and same would apply here.