Series 1 (produced from 1978 until 1980) is commonly referred to as the "SA22C" from the first alphanumeric of the vehicle identification number. Mazda's internal project number for what was to become the RX-7 was X605. In Japan, it was introduced in March 1978, replacing the Savanna RX-3, and joined Mazda's only other remaining rotary engine-powered products, called the Cosmo which was a two-door luxury coupé, and the Luce luxury sedan.

The lead designer at Mazda was Matasaburo Maeda (前田 又三郎, Maeda Matasaburō), whose son, Ikuo [ja], would go on to design the Mazda2 and the RX-7's successor, the RX-8.[2] The transition of the Savanna to a sports car appearance reflected products from other Japanese manufacturers. The advantage the RX-7 had was its minimal size and weight, and the compact rotary engine installed behind the front axle helped balance the front and rear weight distribution, which provided a low center of gravity.