As I reckymember, DKW/Auto Union and Audi sprang from the same original firm, Horch, which also spawned Porcshe and Volkswagen. In the late 1930s, the great Italian Grand Prix driver Tazio Nuvolari, in an Auto Union, pretty much designed by Ferdinand Porsche (who went on to design the WWII Tiger Tank, anong other things), bested both Mercedes and Ferrari on the premiere racing circuits of Europe. SAAB, which during the war built mostly a license version of the German Messerschmidt BF109 fighter plane (popularly, but incorrectly, known as the ME-109), re-incorporated in '47 as an automobile manufacturer (there being then little domestic demand for fighter planes
), but I don't believe the first production car, a "Model 92" was offered for sale untill around early 1950. The chief influence of SAAB's aircraft manufacturing experience was in the area of sheetmetal forming. SAABs gained a reputation for performance and reliability on the rallye circuit, for instance dominating their class in the Paris-Dakkar rallye for years in the '50s and '60s. A silly bit of trivia ... a series of developmental models, built to explore and perfect the transition to 4-cylinder/4-stroke engines, was internally codenamed the "Toad". Another silly boit of trivia; there really is a Trollhatten ... and that's where SAAB has been headquartered sincew its founding, way back when bicycle mechanics Orville and Wilbur from Dayton Ohio were the closest thing to astronauts the world yet had seen.
Amazing what factoids one accumulates as a motorsports fan who happens also to be an airplane driver and a history buff