The RGU Universa was a 2.65 cc sideport diesel which was manufactured during the period 1950-1953 in Unterreichenbach, a town in the Black Forest region of West Germany. The designer and manufacturer of these engines was Rolf Röhner, whose firm traded under the name of Röhner & Gross. The letters of the engine's name presumably stand for Röhner & Gross, Unterreichenbach or possibly Röhner & Gross Universa. The firm went on to manufacture the well-known Jaguar diesels during the mid to late 1950's. Those excellent engines were marketed by Josef Friedrich Schmidt of Munich.

The earlier RGU Universa was a very well-made if somewhat bulky engine having outstanding handling chracteristics. Its main limitations were an excessively high reciprocating weight and an unusually constrictive bypass system. As a result of these issues, vibration levels were abnormally high, while power output was very much on the low side by early 1950's standards. Still, the engine ran very consistently and handled superbly.

A full review and test of this unusual engine appears elsewhere on this website.