For 1971, Ford introduced a newly styled Mustang that had grown noticeably larger and heavier than the model it replaced. Blame it on consumer demand, or perhaps market research, which showed that buyers wanted more room and more luxury from their pony cars than ever before. Not willing to shed the Mustang’s performance image, Ford was quick to play up the earlier model’s racing success in print advertising.
Yes, Mustangs had captured over 2.0-liter Trans Am titles in 1966, 1967, and 1970, but these cars were significantly different from the 1971 Mustang. Compared to the 1970 Mach 1, the new version gained just over two inches in overall length (and an inch in the wheelbase), nearly two and a half inches in width, and roughly 150 pounds in weight.
As any racer will tell you, weight is the enemy of performance. To counter this and retain the Mustang’s quarter-mile dignity, Ford offered a more powerful optional engine for the Mach 1 in 1971, dropping the 335-horsepower 428 in favor of the 375 horsepower 429. On paper, the performance between a 1970 Mach 1 and a 1971 version was close, with the earlier car running the quarter-mile in 14.31 seconds at a trap speed of 100.22 MPH and a pre-production example of the new model delivering a best pass of 14.43 seconds, at 98.68 MPH.
Stopping distance tells a different story. In 1970, the Mach 1 went from 60 to zero in 148 feet. A year later,Road Testreported that 162 feet were needed to slow the bigger pony down, though it’s not clear how variables (such as surface grip) were controlled. For 1970, the Mach 1 wore F70x14 tires and used front discs with rear drums; for 1971, tire size went to F70x15 and brakes were listed as power assisted discs in front and drums in rear.
Not all Mach 1s were delivered with the highest-spec engine; in fact, it’s safe to say that a much higher percentage were purchased with the base V-8. In 1970 that would have been a 351, which made 250 horsepower when equipped with a 2-barrel carburetor. In 1971, the base Mach 1 V-8 was a 302, which produced 210 horsepower.
As for the handling part, period magazines did seem to compliment the new Mustang’s on-road and on-track manners, despite its added heft. Styling wasn’t exactly embraced by consumers, and production fell from 198,239 units in 1970 to 151,484 units in 1971. By 1973, the last year of the “plus size” Mustangs, just 134,867 units were built, though it’s worth pointing out that this was a 9,774 unit increase over 1972. Success would return for 1974, when Ford produced a total of 385,993 Mustang II's.