Benz 10/30 hp racing car, 1921

As part of the resumption of motorsport activities after the interruption caused by the First World War, Benz & Cie. in Mannheim produced various racing cars based on production cars in the early 1920s. In addition to the compact 6/18 hp racing car with a 1.6-litre four-cylinder engine, 1921 saw production of the 10/30 hp racing car with a four-cylinder engine and a displacement of around 2.6 litres.

Sources are still partly contradictory with regard to the exact specification of this engine. For use in the 1921 AVUS inaugural race, it was not an only slightly improved side-valve engine from the production vehicle with a bottom-mounted camshaft and only 34 hp/25 kW that was installed, but a racing engine developed from this power unit with a new cylinder head and sporty "over-head valve" control with overhead valves actuated by pushrods and rocker arms. According to reliable sources, the power output of this four-cylinder engine was 75 hp/55 kW.

The power unit was packaged in an aerodynamically optimised, two-seater body, which was reminiscent of the legendary "Blitzen-Benz" in its overall appearance and in particular due to the pointed rear end. Another characteristic feature of the 10/30 hp racing car was the pointed radiator, which was widespread in Benz cars at the time. This was to achieve particular fame in the Daimler-Benz era, as it characterised all Mercedes-Benz compressor models until the end of the 1930s.

The chassis of the 10/30 hp racing car with pressed steel frame and rigid axles suspended on semi-elliptic springs at the front and rear essentially corresponded to the standard chassis of the touring car. The mechanically operated four-wheel brake system proved to be problematic, as it is said to have worked less efficiently than a good two-wheel brake.

Benz & Cie. entered two 10/30 hp racing cars in the inaugural race on the Berlin AVUS on 24/25 September 1921, which consisted of six individual races with vehicles of different classes. Works driver Franz Hörner won the Class X B race (cars with up to 10 tax horsepower and overhead valves) with one of these. Over a total distance of 157.4 kilometres, he achieved an average speed of 118.1 km/h.