You are driving a car that very few of this group have ever driven, myself included. I can tell you that you have a better than 3000 pound car with a motor the size of a Honda..... response was not what it was built for.
I can tell you that from a professional standpoint, MBs are as cheap to repair as anything going. From many of the posts I have read, many pay a lot more than others. A well informed owner can seriously minimize their auto repair costs both through proper maintenance and through finding the proper repair facility (including one's own garage).
Buying a new car with a warrantee will really reduce your repair costs... for a period. Its a trade off. I can tell you that any car built in the last 5 years will cost considerably more when 5 years old than its predicessors. This is because of all the electronics in ALL late model cars. Many more systems require much more repairs in the long run.
Bosch Master, ASE Master, L1
33 years MB technician