For 1971, the Ford Motor Company rolled out its biggest Mustang yet, with a feature-rich lineup of six models and the mighty 429 cubic-inch Cobra Jet V8. 

For many, this may be a surprising statistic, but at 109 inches, the wheelbase of the 1971 Mustang is only one inch longer than previous models. Also, the overall length is just two inches greater. But compared to previous Mustangs, the ’71 looks enormous, especially the fastback SportsRoof model iwth its dramatic, nearly horizontal roofline. This new Mustang was nearly intermediate-sized in its exterior appearance, and that was by design. Mustang was moving upmarket.

Ford’s product lines were then under the direction of Semon E. “Bunkie” Knudsen, recruited from General Motors by Henry Ford II in February 1968 to serve as company president. Not long after he arrived at Ford, Knudsen visited the studio of Mustang styling chief Gale Halderman, and there he selected a design proposal for ’71 that was nearly six inches wider than the previous pony. The wider platform was was created in part to allow the big-block 429 cubic-inch V8 to fit easily between the front shock towers, and Knudsen was a horsepower man. So while the new Mustang was only slightly longer, it was considerably wider, which no doubt contributed to its hefty visual presence.

For the 1971 introduction there was an ambitious lineup of six models: base notchback hardtop, base Sportsroof coupe, convertible, a new luxury-trimmed notchback coupe called the Grande, the sport-oriented Mach 1, and the Boss 351. Intended, in theory at least, to replace both the Boss 302 and Boss 429, the Boss 351 was available just one way, as a SportsRoof with a 351 CID H.O. V8 rated at 330 hp and paired to a four-speed manual transmission. However, the Boss 351 proved to be a one-year deal, as it was dropped for ’72 after just 1806 examples were produced.

For the rest of the ’71 Mustang lineup, a full range of Fomoco engines was available, including a 250 CID inline six, a 302 CID V8 (base engine in the Mach 1) and a pair of 351 CID V8s rated at 240 hp (two-barrel carb) and 285 hp (four-barrel). For the big-block V8 crowd, there were two wedge-head 429 CID V8s, the CJ and the CJ-R (the R signifies a ram-induction hood). Rated at 370 hp, these Cobra Jet V8s featured four-bolt mains and an 11.3:1 compression ratio, requiring premium fuel.

The ultimate was the rare 429 Super Cobra Jet aka Drag Pack, which included a Holley carb and a solid-lifter cam and was rated at 375 hp. Alas, the 429 V8s were a one-year deal, too. For ’72 and ’73, as the muscle car era was drawing to a close, the most powerful engine available was a 351 four-barrel V8 that ran on regular gas.

While collectors today seem to favor the Sportsroof models, the notchback and the convertible were respectable sellers in their day as well. In fact, the notchback Hardtop and vinyl-topped Grande (above) models outsold the SportsRoofs by a comfortable margin through all three years of the ’71-’73 product cycle. The Hardtop was the best seller of all, thanks no doubt to its low list price in the $2700-$2900 range and decent standard equipment, including bucket seats and carpeting.

Knudsen’s Mustang made its official debut on August 20, 1970, but by then, Knudsen himself was already long gone. After losing a power struggle with fellow Ford executive Lee Iacocca, who had deeply resented being passed over for the top spot, Knudsen was dismissed by Henry Ford II in September of 1969, nearly one year earlier. Iacocca had his own ideas for the Mustang, including a complete change in direction for the pony car he helped to create back in 1964. You can find more about the 1974 Mustang II here.