Benz 100 hp "Prince Heinrich" car, 1910
After the idea of a handicap for factory drivers, which was practised at the 1909 Prinz-Heinrich-Fahrt, caused some displeasure, this passage was removed from the regulations for the next event. The third Prinz-Heinrich-Fahrt was held from 2 to 8 June 1910 over 1945 kilometres on the route Berlin–Braunschweig–Kassel–Nuremberg–Strasbourg–Metz–Homburg von der Höhe.
Benz & Cie. once again took part in the third edition of the Prinz-Heinrich-Fahrt with a delegation of ten specially designed touring cars. Four of them were equipped with a 5.7-litre engine with 80 hp/59 kW and the other six with a 7.3-litre four-cylinder engine with an output of at least 100 hp/74 kW. Instead of the previously favoured chain drive, both variants now featured a cardan drive for the rear axle. The bodywork was influenced by the "Blitzen-Benz" and featured both a streamlined water box on the radiator and a pointed rear end.
The engine of both variants had a remarkable design feature: it was the first engine designed by Benz & Cie. with four valves per cylinder. With this ultra-modern design, the Mannheim-based company was years ahead of many of its competitors, including Daimler-Motoren-Gesellschaft. It was not until 1914 that the first four-valve engine was used at DMG: in the Mercedes Grand Prix racing car that has remained a legend to this day.
The design details of the Benz Prinz-Heinrich-Wagen are particularly well documented, as one of the 100 hp cars was examined in detail in the Laboratory for Motor Vehicles at the Technical University of Berlin in 1911 and the results subsequently published. Its maximum engine power output of 104 hp at 2050 rpm and particularly high operating efficiency were measured on the university's dynamometer.
With the exception of the extremely advanced engine design, however, the Benz special touring cars were largely conventional in design. Despite its large displacement and a rated speed of over 2000 rpm, the long-stroke four-cylinder had three crankshaft bearings and the mechanical brake system only acted on the rear wheels and the transmission output shaft. According to reputable sources, the top speed recorded for the 100 hp cars was around 135 km/h.
Despite the considerable efforts put in by the factory, the success of the 1910 Prinz-Heinrich-Fahrt fell well short of expectations. A 100 hp car driven by Arthur Henney crossed the finish line in 8th position as the best 7.3-litre car after a total distance of almost 2000 kilometres. Fritz Erle, the best Benz driver in one of the 5.7-litre cars, came in three places behind three Austro-Daimlers and an Opel.
After this last "Prinz-Heinrich-Fahrt", which was organised in the usual manner, Benz & Cie. officially withdrew from the event. In 1911, the tour was organised purely as a touristic trip without any sporting aspect. Most of the factory cars were subsequently used in various races and touring events and were then sold to privateers with sporting ambitions.
One of the vehicles fitted with the larger engine was converted in 1910 into a one-off model with chain drive following an accident. This was then put into use on various occasions and remained in the company's vehicle collection until it was lost in the turmoil of the Second World War.