I wonder if the trend holds for the lower end of the classic car market as well — i.e. not Bugattis and Grand Prix winners but production line Porsches and Chevrolets and stuff.
I dunno. All I know is I bought and sold a few muscle cars in my teens for under a thousand dollars that, with a detailing job and some new tires probably would have gone for 20 or 30 times that 20 years later.
I never bothered to figure out the rate of return that would have represented...