Despite being the approximate speed of molasses but less deadly, a 1973 Saab 96 trundling around Boston, Massachusetts will either delight fellow drivers or raise bewildering, rubbernecking confusion.

If you were to spectate a European rally event during the early 1960s, you’d have heard the distinct buzzing, brapping yelp of a certain two-stroke engine bouncing off the hills and trees and echoing ...