The Mustang II (1974-1977) wasn’t the favorite generation, and lots of people still call them a disgrace compared to the previous or later models. That is why those cars are rarely on the silver screen. However, one of the few times Mustang II was cool was when it was in “Starman” with Jeff Bridges, who played an alien who drives a copper-colored Mustang Cobra II (via IMCDB).
The downsizing of the whole Mustang range meant the introduction of economical four-cylinder engines. Ford also did some part-sharing with other Ford models. This helped the model survive the recession of the ’70s as well as the death of the muscle car movement.