I have a 2002 MB C240 Sedan with 45K miles with no major problems thus far. Since I commute alot (16K miles a year) I plan to drive this car until it falls apart. My question to people who have experience with Mercedes cars is: How long do you speculate this type of car would run for until it becomes too costly to fix?

If you maintain it well it will run for at least 150-200K without major problems but you should expect some more spendings later on. I mean stuff like "Check engine" light, airflow sensor and other more or less minor stuff are common.