After I'd looked for a while, I decided that a 280SEL 4.5 was the right car for me. There were lots of them out there, which meant parts were going to be relatively easy to find. They were considerably undervalued ("Who wants an old Mercedes that's too expensive to fix?"), collectors say 4-doors are "worthless". 5 grand will get you a real creampuff. and they weren't as difficult to maintain as the 6.3 was. The 4.5 engine is generally regarded as bulletproof, designed to run at 3/4 throttle for up to 500,000 miles, which is far above US highway speeds. 4.5's routinely turn in over 3 or 4 hundred thousand miles, and they came from an era of totally shitty cars that never lasted beyond 90,000. Best of all, it was a long distance runner with a big V8, easily able to cruise at 80 MPH.