I have some interesting observations about the longevity and durability of American, Japanese, and Mercedes cars.
People in my family seem to own cars for a looooong time. My father was a mechanic for Unocal and loved to work on his cars when I was a kid. He owned cadillacs through the late 60's, and seventies. We seem to put a lot of mileage on our cars. All of his cadillacs went over 200,000 miles. My mother even had a VW Beetle that went over 200,000 miles on the original engine. My father also drove a 1981 300 SD for 399,000 miles until he sold it. It started to cost a lot of money to keep runnning, but, hey, it had 399,000 miles on it. My mother recently traded in her 1994 C220 with 244,000 miles for a 1999 E430. I have driven two Toyota Camry's - one to just over 200,000 miles (straight 4) and one with about 255,000 miles (a V-6). These were extremely trouble-free cars, and the only repairs I made were shocks, struts, rotors, one starter, one alternator. My 93 300E 3.2 has almost 131,000 miles.
My personal experience is as follows:
The American cars, in particular, at high mileage feel like they are going to fall apart. The suspension is shot, the chasis creaks and shakes, etc. They are without a doubt not worth repairing and maintaining because the cars feel like they are falling apart.
The Japanese cars were of the highest quality and trouble free hands down compared to Mercedes and American cars up to even 200,000 miles. The problem is after 200,000 miles, they are very "tired", loose, doors close with a shake and a rattle. The styling is also really starting to show its age.
The Mercedes we've owned in my family, including mine, have had more repairs, easily, compared to the Japanese cars, but as they go up in mileage, they never lose their solid feel, the doors always close with a solid "thud", the styling still looks timeless, and they still hold their value.
In summary: American cars are waaaay behind the Japanese and Mercedes, the Japanese, in my opinion have higher quality than either the Americans and Mercedes, and Mercedes have higher incidence of repair, but are much more durable and have greater longevity. They still feel "new" even at incredibly high mileage. J.D. Power and Associates, Intellichoice, Consumer Reports, etc. have all consistently ranked Japanese cars higher in quality than Mercedes. My heart is with Mercedes and I hope they get their act together relating to quality.