Most of the interior and exterior designs on the 1971 Ford Mustang were largely influenced by General Motor design cues, adding a different feel to the car as well. Performance in 1971 still existed, with the Mach 1 and Boss 351 editions, though the Boss 351 was canceled mid-year. This was the last year for Big Block V-8s in Mustangs. A convertible Mustang still existed, though was unpopular with customers. Sales dropped to just below 150,000 for 1971.
As the government continued to enforce stricter fuel economy standards across all manufacturers, performance continued to suffer for most of 1971 compared to previous model years, all while the car continued to get heavier.
The Ford Mustang remained unchanged from 1971 to 1972. All in all, performance dropped significantly. Several reviewers noted that the new 1972 Ford Mustang still ended up performing decently. A handful of minor revisions to trim and features, sales continued to drop for the 1972 model year, ending up hitting a new low of 125,813.
1973 announced the last year for this design. Overall sales ended up being just below 135,000, which was a little higher than the previous year. The movie 'Gone in 60 Seconds' also made an icon out of a 1973 Mach 1 Mustang nicknamed 'Eleanor' and popularized many 1973 Ford Mustangs.
Other changes to the 1973 Ford Mustang emphasized safety. Along with the new front bumper, new upholstery and several other minor interior modifications were made in order to comply with federal safety requirements. These additions didn't effect the cost of these 1973 Mustang parts drastically, which allowed the popular muscle car to still remain affordable to the masses.
Performance changes in 1973 had negative feedbcak. The federal government steadily continued to clamp down on high polluting engines, like many that were under the hood of this Mustang. While these tweaks negatively impacted performance.