BMW E34 M5

The M5 to me is the ultimate touring car -- large and elegant, fast and a bit menacing. I like the original e28 M5, but it looks light and sporty enough to not really convey that sense of imposing touring car. The e34 is more stately, but still with the beautiful older-style grill and round headlights (unlike the other BMWs that would follow in the 90s and beyond).
Mine would be black, the only proper color for this car, in my opinion. Hell, throw in an old-school e28 M5 and the super-elegant e39 as well. I'd say add an e60 too, but that car with its many many HP and V10 and so on seems too over-the-top. maybe the e63 M6.