The BMW 503 is a two door 2+2 seater sports car unveiled by BMW at the 1955 Frankfurt Motor Show. Production got under way during the summer of the next year, and by 1959, when the 503 was withdrawn, 413 had been built, including 139 cabriolets;

The car was styled by the entrepreneurial auto-designer, Albrecht von Goertz, based on preliminary drafts prepared by Kurt Bredschneider.^{[citation needed]} It was originally intended to feature a flamboyant shape incorporating rounded mudguards which would have emphasized its kinship with the BMW 502 sedan, but regulations concerning matters such as light positioning rendered such a form impractical. In retrospect, the more square cornered look of the car as it emerged with fully integrated wings may have been more in tune with future styling trends than the original proposal.^{[citation needed]}

The 503 incorporated the 3168 cc light metal V8 engine from the 502 which in this application delivered a claimed power output of 140 brake horsepower (100 kW) and acceleration from standstill to 100 km/h (62 mph) in 13 seconds along with a top speed of about 115 miles per hour (185 km/h). The four speed manual transmission was unchanged from that used in the 502,^{[citation needed]} and was originally mounted remotely from both the engine and the rear axle, as on the 502. In September 1957, the drivetrain was redesigned, with the transmission being bolted directly to the engine, as with the 507, and with the shifter being relocated from the steering column to the floor.