The Ford Mustang grew in size and significantly restyled for 1969. Performance was the priority and mechanical and exterior changes reflected this goal. There were quad headlights and the side scoop was now located high on the rear fenders of the fastback models. It remained in the same position on hardtops and convertibles but now faced rearward. The Mach 1 came with a 351 cubic-inch V8 engine rated at 250 horsepower with the Motorcraft two-barrel carburetor. With a four-barrel carburetor, the 351 CID developed 290 horsepower. This would prove highly successful and more than 72,000 examples of the 1969 Mach 1 Fastback were sold.

Mach 1 sales dropped for 1970, partly due to a saturated market. Of the nearly 42,000 examples built, 2,501 were powered by the Shaker-scooped 428 Cobra Jet big-block engine. The 1970 Mach 1 had received slight restyling, which brought back the two-headlight front end. There were grille-mounted driving lights, black hood paint and decal stripes, hood scoop, twist-type hood locks, aluminum rocker panels, color-keyed racing mirrors, blackout honeycomb rear panel, pop-open gas cap and oval exhaust tips. They had a 4-speed manual transmission, a 9-inch rear axle with 3.50:1 gears in Traction-Lok differential, and a competition suspension. Inside were vinyl bucket seats, console-mounted shift controls, and Deluxe steering wheel with rim-blow feature.