The automobile auction market, like basically all other collectible markets, reached new heights earlier this year. In May, a 1955 Mercedes-Benz 300 SLR known as the Uhlenhaut Coupe sold for $142 million. The mind-boggling sum didn’t just beat the previous mark—it demolished it by nearly $100 million.

It’s unlikely many expected the silver gull-wing Benz to sell for as much as it…