The Road Runner — named for the famous bird from "Looney Tunes" — was a hit for Plymouth in the late 60s and early 70s.

Yet the worst-selling muscle cars of all time fell far short of this. When determining muscle car sales figures, the first challenge involves deciding which cars belong in this category.

The early 1970s saw some of the best muscle cars in history like the ... and it's worth exploring exactly what cars exemplified the worst the automotive industry had to offer, and what made ...