The 1960 Corvair 569 and 769 series four-door sedans were conceived as economy cars offering few amenities to keep the price competitive, with the 500 (standard model) selling for under $2,000. Powered by the Chevrolet Turbo-Air 6 engine with and mated to a three-speed manual or optional extra-cost two-speed Powerglide automatic transmission (RPO 360), the Corvair was designed to have comparable acceleration to the six-cylinder full-sized Chevrolet Biscayne. The Corvair's unique design included the "Quadri-Flex" independent suspension and "Unipack Power Team" of engine, transmission, and rear axle combined into a single unit. Similar to designs of European cars such as Porsche, Volkswagen, Mercedes-Benz, and others, "Quadri-Flex" used coil springs at all four wheels with independent rear suspension arms incorporated at the rear. Specially designed 6.5 by 13-inch four-ply tires mounted on 5.5 by 13 inch wheels were standard equipment. Available options included RPO 360, the Powerglide two-speed automatic transmission ($146), RPO 118, a gasoline heater ($74), RPO 119, an AM tube radio ($54), and by February 1960, the rear folding seat (formerly $32) was standard. Chevrolet produced 47,683 of the 569 model and 139,208 769 model deluxe sedans in 1960.