Take a 1951 Mercury and customize the hell out of it with flame paint, all new interior and one hell of a price tag – and you get a Merc Lead Sled.
Originally, the lead sled referred to extensively repaired/modified cars due to the use of lead as body filler and was, for the most part, an insult.
Since the introduction of man-made fillers (such as Bondo), the term has come to mean a post-war, large (full size) American car of the 40s, 50s and early 60′s (generally up to (but not including) the 1965 model year). A lead sled tends to have all extra side moldings shaved off and filled with the suspension lowered. Lead sleds are built for style, not speed. Some common lead sleds are the 1949/1951 Mercury, 1949 Ford and the 1959 Cadillac. (Source: Wikipedia)
Many Mercury Eights (Mercury 8) vehicles from the 1949 to 1951 models have been transformed into Merc Lead Sleds – and used in various films, including “Cobra” starring Sly Stallone, “American Graffiti” “Rebel without a Cause” and was the inspiration hind the original (pre-Adam West) Batmobile.