I too prefer my Mazda 929 for long trips. It is entirely unfrantic at speed. My 83 300D though is nice in the winter with the windows up. It does feel a lot more solid at warp speed. My best drive this past season though was with my 58 220S, 750 miles, lots of highway at 75~80, and SMOOOOTH!! Quiet and nice driving. It's a hand-full/foot-full in town driving with no power steering and a 4-speed manual but it does shine on the highway. My other 300, a coupe has a noisy engine needing a little injector work maybe. The front-end is getting some work next summer, mostly just minor bushing work. It is actually a great driver other than it wanders a bit. My all time best drive ever in my life was bringing a 62 Rolls from RI to Fla for a guy I worked for. Rode much better than any car has a right to.