In 1966, an Ohio man parked his 1940 Packard Super 8 sedan in a salvaged gasoline storage tank and welded it shut. He opened it six months ago, and the restored Packard might now be worth $50,000.
Inflation means that an assumed 1940 purchase price of $2,500 is equivalent to $38,400 today. Add in the restoration costs and this Packard has just kept up with inflation and nothing more. Closed sedans just aren't that desirable on the collector market.