Detroit in the 1950s and early 1960s had a strange habit. It built its plainest, cheapest family cars, the ones with rubber mats and dog-dish hubcaps, and then let buyers order the biggest engine in the catalog for them. Sometimes that was for racing rules. Sometimes it was simply because the order form allowed it. The result was a generation of sleepers. Here are eight of them, in the order they appeared, with a note…