Adolf Rosenberger was a successful businessman who mainly raced Mercedes and Benz cars in the 1920s. His successes and records included wins at Avus, Stuttgart Solitude in 1924 and 1925, the Kasseler Herkules Hillclimb and the Klausenpassrennen. At the 1926 German GrandPrix Adolf Rosenberger was involved in one of the numerous accidents in treacherous conditions. He survived a crash into a marshals hut, but the death of three people had Berlin’s Avus track closed down for racing, for decades.
In 1931 he founded the Porsche GmbH together with Ferdinand Porsche and Dr. Anton Piëch(Rosenberger became porsche's business manager). He was also instrumental in the creation of the Auto Union concern. But the turmoils of WW2 forced him into exile. He became an US-citizen under the name of Alan Arthur Robert and passed away in California in 1967.
Born: 8th of April 1900 in Pforzheim, Germany.
Died: 6th of December in California, USA, aged 67.
Wikipedia
Also found this
pdf file, on go get papers websearch, pages of interest would be page 5 & 9.
Hope this helps.