Forty years ago this fall, a completely redesigned second-generation Ford Mustang hit the road. Mustang II was a radical departure from the 1973 model it replaced – 19 inches shorter, 500 pounds lighter and, for the first time, not available with a V8 engine.

Despite being among the best-selling Mustangs of the past 49 years, Mustang II has been maligned by hardcore pony-car fans as the black sheep of the family almost since it went on sale. Looking back now, however, it’s clear that without the new direction forged by Mustang II, Ford almost certainly wouldn’t be celebrating 50 years of Mustang today.

Growing up too fast
The Mustang debuted in 1964 as a stylish, lightweight and affordable sporty car. It was nimble and quick, offering a choice of V6 or V8 engines generating up to 271 horsepower. Starting at just $2,368, with seemingly infinite possibilities for customization, Mustang roared out of the gate with sales of more than 1 million units in less than two years.

Competitors took note. Hoping to cash in on the obvious demand for performance cars, they quickly upped the ante, offering larger and more powerful big-block V8 engines. Ford engineers followed suit, beefing up the Mustang platform to support engines as big as 429 cubic inches. Along the way, Mustang got more than a foot longer and nearly 700 pounds heavier, losing much of its nimble character.

While demand for big-engined muscle cars was strong at first, it tapered off quickly by the end of the 1960s and Mustang was losing the broad audience that had made it such an early success. Sales dropped from a peak of more than 600,000 in 1966 to just over 125,000 by 1972.

But customers were not happy with the direction Mustang was headed as early as May 1968, when investor Anna Muccioli took the floor at Ford’s annual shareholders meeting to query company executives. Her comments were included in a Ford Educational Affairs department paper about Mustang:

“I have a ’65 Mustang and I don’t like what’s happening. They’re blowing them up. Why can’t you just leave a sports car small? I mean, you keep blowing them up and starting with another little one, blow that one up and start another one. I mean, why don’t you just leave them?”

Back to its roots
At the same time, demand for small cars was growing, representing 40 percent of the U.S. market by 1973, up from 23 percent in 1964. By 1972, subcompact sales had doubled in just five years.

Coping with dissatisfied Mustang enthusiasts, and the emergence of federal environmental and safety requirements, Ford realized that Mustang needed to return to its roots. Initial proposals for a redesign based on the 1971 to 1973 platform were scrapped. A smaller, lighter car was created.

While no one could have predicted a Middle East oil embargo in 1973, or the subsequent spike in gas prices and demand for smaller cars, the arrival of Mustang II and new more fuel-efficient four-cylinder and V6 engines could not have been better timed.

Mustang II lacked the brute-force acceleration of its immediate predecessor, but its trimmer dimensions restored some of the agility of early Mustangs; overall performance was actually comparable. One year after Mustang II’s debut, eight-cylinder power returned to the pony car with an available 302-cubic inch, small-block V8.

Displaying styling cues that recalled the original 1965 models, Mustang II sales topped more than 285,000 vehicles in 1974 – more than double the previous year – and remained strong enough the next several years to justify development of another all-new model for 1979.

In recent years, the popularity of so-called “malaise-era” cars like the Mustang II has increased as people realized its tidy dimensions and light weight make a great platform for a fun performance car.

“While the first generation Mustangs are often restored to original condition, a higher percentage of Mustang IIs get modified with more powerful engines, better brakes and upgraded suspensions,” said John Clor, Ford Racing enthusiast content manager and Mustang historian. “People are finally recognizing the critical role that Mustang II plays in the pony car lineage.”

Following the introduction of Mustang II, the Ford Educational Affairs department prepared a paper that analyzed the development of the original and second generation Mustang. Click here to read the full text.