The top-selling models of the Mercury Cougar are from the fourth generation of the car when the vehicle was based on the Ford Torino platform. The largest production run of the Cougar was in 1978, with 213,270 examples produced.
Part of the reason the fourth-generation Mercury Cougar was the best-selling iteration of the vehicle was that there were many more Cougar models than in any previous or subsequent generation. Almost every mid-range Mercury model was designated a Cougar, including station wagons and four-door sedans. The classic XR-7 coupe design still accounted for the majority of Cougars, with 166,508 of these produced for the 1978 model year.