Once cars hit the bottom of the depreciation curve, and people all of sudden want them as a collectors item, values skyrocket. And seemingly go up forever, whether or not the classic car market is a bubble notwithstanding. So what car is up and ready to hit that upward part of its life?
While they are on the slow march up I think the e34 M5 has a lot of meat on the bone, nice examples car still be in the mid teens and solid drivers can be found around 10,000 when they come up for sale. And as it turns out, it came in purple, which makes it awesome-er.