The exterior design was penned by Carl Cameron, who was also responsible for the exterior designs of the 1966 Dodge Charger. Cameron based the 1970 Challenger grille on an older sketch of a stillborn 1966 Charger prototype that was to have a turbine engine. The pony car segment was already declining by the time the Challenger arrived. Sales fell dramatically after 1970, and though sales rose for the 1973 model year with over 27,800 cars being sold, Challenger production ceased midway through the 1974 model year. A total of 165,437 first-generation Challengers were sold.