Apologies for my late reply..
That's what Tragatsch's book reveals about Imperia:
In the 19-mid-thirties Dr.-Ing. Rolf Schroedter constructed new motorcyle two-stroke engines of unusual design. Unfortunatley he invested more money and time in that engine project than the small Imperia firm was about to bear.
Due to circumstances it wasn't possible to import race engines from foreign countries, so he was 'forced' to built his own. In addition to that he also constructed prototypes of small racing cars. First equipped with JAP two-cyl. engines these were about to have Imperia radial engines with 750cc later. Bark of Dresden were Imperia's engineering partner back then.
Imperia planned to built sports cars in mass production and streamlined single-seat-racing cars.
They got support from Koenig-Fachsenfeld. According to Tragatsch he was involved in areodynamics of all Imperia racing projects.
Due to financial problems Imperia went bust in 1935 before the engine was well engineered and reliable. None of the Imperia cars ever raced.
My guess would be 1934 for that small single seater. Maybe a year earlier, but not much more.
