At the time, both Ford and Mercury were vastly improving the aerodynamics of thier cars to gain an edge on the competitors. To keep up Dodge created the 500 model for the NASCAR circuit.
The Charger 500's aerodynamics were improved over the normal Charger's by adding a 68 Coronet grille and headlight assembly, which was flush mount, instead of the charger's usual recessed flip headlights. The rear window was also made flush with the C pillars, to reduce turbulance of air coming over the roof. This feature was also carried over to the Charger Daytona model, which enhanced aerodynamics even more after the 500's dissapointing lack of domination.
Power choices to the production models were limited to the 440ci big block or the 426 HEMI
Back then (when NASCAR was cool :rolleyes) Manufacturers had to sell at least 500 copies of the special models they raced, in today's terms, Ford would be required to make 500 V8 powered RWD Tauruses. This 500 production run is where the Charger 500 got its name. Because Dodge did not use these cars for the entire season (the latter half was raced with Charger Daytonas) only 392 of them were made. Most of the cars were turned into the Charger Daytonas as well, so very few are left.
note the round headlights that are flush mounted and the flush mounted rear window
