Hans Rohrbach built his motorcar with an 8-24 PS NAG engine.
I've found this picture on an Auction webpage, for 4.000 Euros:
"HANS ROHRBACH
Original photo album with 91 original b / w recordings; Design drawings of a motorcar designed by Hans Rohrbach with 8/24 PS NAG engine, all recordings stamped with Hans Rohrbach Oberingenieur, including recordings of the finished vehicle, details of eg cardan head, shock absorbers, steering, gear selector, differential head, rear axle guidance, convertible top , Etc, a replica of the vehicle through these documents is quite possible, highly interesting"