This one's easy for me. I have always said the 63-64 Buick Electra 63-64 Oldsmobile 98 are very underrated. I am not saying this is a bad thing, though, as you can find a very nice unrestored fully operational loaded one of these for under $5000, sometimes they are almost give-away priced. I love the way these two cars drive down the highway, and have personally put over 120,000 miles on a 64 Electra coupe with no, and I am serious, no major mechanical problems other than needing some brake pads and general tune-up stuff. These cars look great in convertibles, coupes, and 4 doors. The 64 98 and 64 Electra 4 door 4 window hardtop is a great and sporty looking car. 1960 Edsels are also underrated to me. Yes, I know, it is a 60 Ford with a goofy grille and stretched 60 Pontiac taillights, but unless it is a convertible, their prices don't reflect their obscenely low production numbers. There are definitely more, but these are the two that first jump to mind.