The Mini was conceived as a basic car that would cost little to build. Where it innovated was the requirement laid down by management that its length should be 10 feet (about 3 m) long and that the passenger area measure six feet (1.8 m) long, a large ratio at the time (late 1950s). The design task was handed over to Alec Issigonis who conceived the idea of using front wheel drive and mounting the motor transversely, rather than in a fore-aft orientation as was the industry norm.
Mini buffs probably know if or to what extent stylists were brought into the project. Given 1957 vintage body stamping capabilities in Britain plus the "package" mentioned above and the need to have the car cheap to build, the result was a crude, stamped-out general appearance. The only evidence of styling input that I notice is in the grille, its surrounding area and the shape of the taillights.
So the Mini counts in my book as one of the few post-1950 mass production cars whose appearance was actually designed rather than styled.