World’s first series-production car with a diesel engine
Fifty-years after Carl Benz invented the petrol-powered automobile, the W 138 series 260 D was presented at the 1936 International Motorcycle and Automobile exhibition in Berlin. It was a revolutionary car powered by a 2.6-litre OM 138 four-cylinder engine with the Mercedes-Benz pre-chamber system and Bosch injection pump, which developed 33 kW at 3200 rpm.
The 260 D was remarkably efficient too, using just 9.5 litres of diesel per 100 kilometres, which meant a full tank provided for a range of 400 kilometres. The range was increased to 500 kilometres on a single tank after modifications to the 1937 model 260 D.
Such fuel economy was significant even in 1936, especially if you were in the taxi business. For holders of a passenger transport licence, diesel fuel cost just 17 Pfennigs per litre, or less than half the standard cost of petrol – so the 260 D became the vehicle of choice for the emerging taxi fleets across Germany.
Mercedes-Benz also released a six-seat Pullman saloon car from the start of 260 D production, which became a favourite with taxi companies, although private buyers also took a liking to this and other versions of the model due to the economical nature of the car.
The upgraded 1937 car was more a facelift of the 260 D, with a new radiator grille and smaller headlight housings. There were also two 6/7 seat Pullman variants, which were now given a more luxury treatment.
Other interesting modifications to the standard 260D included a wider track and the front and rear, as well as a larger 50-litre tank, which was thankfully moved from the engine compartment to the rear of the car.
Further improvements were made on the 1938 model, which got a fully synchronised four-speed transmission, wider wheels and tyres, and dual-action shock absorbers at the rear.
Cold starts in the thick of winter would also prove easier, with the introduction of electrically heated glow plugs on the 1938 car.
The 260 D was a major success story for Mercedes-Benz, with no less than 1967 units produced from 1936 to 1940. For private buyers and taxis alike, it became the long distance king – as there was still plenty in service during the 1950s.
Over the years Mercedes-Benz has continued to push the development of the diesel powerplant with innovations, which included the first five-cylinder diesel car in the 240 D 3.0 in 1974 and the introduction of common-rail injection with their C 220 CDI in 1997.
More recent innovations in the company’s diesel powertrains have been with the Blue-TEC emissions control in the E 320 BlueTEC in 2006 and the highly advanced E 300 BlueTEC HYBRID for a 2011 launch.