Some interesting choices. All, IMO. I would agree that the 1970 – 1973 Datsun 240 Z are underrated. They had a cool design and were fast.
1969 – 1970 Ford Mustang Mach 1 are somewhat underrated but they are not a Shelby. I think the 1964 – 1970 GTO have always been undervalued compared to the Chevelle SS. That is because more Chevelle’s were sold, not because it was any less of a car. As far as the Triumph TR6’s I have heard the quality just wasn’t there in their manufacturing. I believe the 1972 – 1975 Porshe’s also had quality issues. Big American convertibles are under appreciated. They may not be performance cars but they had allot of style. Station Wagons are a very interesting group, interest and price have started to rise. I think everyone would agree that pickup trucks have been rising price-wise and interest-wise greatly in the last couple of years. You see more and more at local car shows and cruises.