I'd say the low mileage is pretty indicative of most super hard suspension set up cars. If you do more than 10/12k a year you probably do it for a living or like touring. At which point comfort tends to take over. These cars are not relaxing drives
Even a gt3 rs comes all leathered up and the next one with a PDK. Why wouldn't you want the toys even for 10k a year. I wouldn't buy the c63 if I was a high miler...I'd buy a diesel as you'd be doing the distance to make it count. But even as a mid miler i wouldn't, and that's for comfort not cost....you do have to do a decent mileage to make a significant financial difference between petrol and diesel. At 14k per annum to 20k it is because you are doing enough mileage that comfort really is a factor. When I did, I had a ml320 CDI. Not exactly a hyper mpg machine. All IMHO of course.