Mustang 428 Cobra Jet
In the middle of the 1968 model year, the 427 engine was retired and replaced with the 428 Cobra Jet, a big block that had a ram air hood scoop. Per insurance regulations, it was rated at 335hp, but it was actually a lot stronger. It could do a 13.5 second quarter mile, enough to earn it the praise of Hot Rod Magazine. The Cobra Jet was the brainchild of Bob Tasca, who at the time was the biggest Ford dealer in the country. He'd been sponsoring Mustang drag cars, which were tearing up drag strips in 1965-1966; his success brought many customers into his show room. Tasca accepted the 390 option, but he didn't think it was strong enough to contend on the track.
When one of his employees burned up a 390 car, Tasca asked his mechanics to put together an engine consisting entirely of parts that could be bought from the Ford catalog. They began with the Police Interceptor 428, and added low-rise heads, a Holley carburetor, and a camshaft from a 390. The resulting car ran a 13.39 second quarter mile, enough to catch the eye of those in Dearborn. Tasca's car was used as the template for the Cobra Jet that made it into production.
Around the same time the Cobra Jet was released, a 302 with bigger valves, high compression heads, and double four-barrel carbs made it onto the market. It was dubiously rated at 240hp, it was Ford's ace in the hole for the Trans-Am series. Unforeseen difficulties delayed its production after SCCA approval, and few were sold its first year. There were over 300,000 cars sold for the 1968 model year, a number far below that for 1965-66.
Despite sluggish sales, the optional equipment market was growing. That signaled a trend where buyers were focusing less on economical sportiness, and more on luxury options and convenience. Cruise control came on 72% of 1968 Mustangs, and four-speed manual transmissions came on just 4% of cars from that year. Mustang buyers were less worried about price and performance than they were with looking good and going fast.