1. Mercedes-Benz, the future of the automobile
2. Daimler: engines, carburetors, radiators and transmissions
3. Benz Patent Motor Car, the first automobile
4. The 35 hp Mercedes, the first modern automobile
5. Evolution of the automobile
6. Supercharged engines by Mercedes
7. From independent wheel to active suspension
8. Diesel passenger cars
9. Direct gasoline injection
10. The road to passive safety
11. Holistic accident research
12. Alternative drive systems
13. Milestones of innovation at Mercedes-Benz

Diesel passenger cars (since 1936)

Rudolf Diesel was granted a patent for the compression-ignition engine named after him in 1892, and the first diesel engine ran successfully one year later. In this power unit the fuel was blown into the combustion chamber under high pressure by a so-called injection compressor, and this principle was at first only suitable for large stationary and marine engines.

Prosper L’Orange, an engineering genius with a passion for the diesel engine and an employee of Benz & Cie. from October 1, 1908, was the inventor of prechamber injection. It was the most important step towards the vehicle diesel engine. Between 1919 and 1921, until the first high-speed vehicle diesel engine was a reality, L’Orange made three further, important inventions: the funnel prechamber, the needle injection nozzle and the regulated injection pump.
The world’s first diesel truck was a Benz five-tonner with a four-cylinder prechamber diesel engine which generated 45 hp (33 kW) at 1000 rpm and ran successfully for the first time on September 10, 1923. It required approximately 25 percent less fuel than a comparable five-tonner with a gasoline engine. From 1926, after the merger with Daimler-Motoren-Gesellschaft, the prechamber principle developed at Benz & Cie. was the basis for production of truck diesel engines by the new Daimler-Benz corporation.

In 1936, 13 years after the introduction of the first diesel-engined truck, the Mercedes-Benz 260 D, the world’s first production diesel car, was shown at the Berlin Motor Show and caused quite a sensation. Its 2.6 liter four-cylinder power unit with the Mercedes-Benz prechamber system and a Bosch injection pump had an output of 45 hp (33 kW) at 3200 rpm and was installed in the chassis of the 200 gasoline model. Its average fuel consumption was slightly more than nine liters per 100 kilometers, considerably bettering the 13 liters of the gasoline-engined 200. In 1936 the price of diesel oil was only 17 pfennigs per liter, less than half that of gasoline. No wonder that particularly taxi drivers fell in love with this car on the spot, and since then Mercedes-Benz diesel cars always played a leading role in this segment. The diesel’s reliability in hard day-to-day taxi operations also attracted private customers into the showrooms. Approximately 2000 units of the Mercedes-Benz 260 D were built up until 1940.

After the war, economic efficiency was in greater demand than ever before, and the four-cylinder passenger car diesel engine continued its great success in the Mercedes-Benz 170 D from 1949 and the 170 DS from 1952. These were followed by the 180 D and 190 D in the three-box body of 1953. With the “tailfin” model, the /8 and the successor series, production figures of the diesel engine rose continuously, and it ultimately became an indispensable part of the mid-sized Mercedes series, i.e. the current E-Class. Constant improvements, larger displacements and increasing output levels, reaching a respectable 2.4 liters and 65 hp (48 kW) as early as 1973, continuously adapted it to the wishes of customers. The competitors also gradually acquired a taste for it.

In 1974 Daimler-Benz offered performance-hungry diesel drivers 80 hp (59 kW) and a new quality of smoothness with the three-liter five-cylinder engine. Another 8 hp (5.9 kW) were added in 1979. The first Mercedes-Benz passenger car with an exhaust gas turbocharger was the model 300 D Turbodiesel (W 123 series). With an output of 115 hp and torque of 250 Newton meters, the passenger-car diesel engine made it into the S-Class in 1977 – initially exclusively available in the US market.

The end of 1982 saw the introduction of the compact class, the forerunner of the current C-Class, with two gasoline models which were followed by a new, 75 hp (53 kW) two-liter diesel in 1983. This engine was the first to be fully encapsulated, providing a new quality of exterior and interior comfort in a diesel car as engine noise was reduced by approximately half. With this “whispering diesel” Mercedes was once again ahead in the race, its pioneering spirit unbroken.

In April 1993, the first car diesel engine with four-valve technology and electronic engine management, known as Electronic Diesel Control or EDC, appeared on the scene. Thanks to four-valve technology the new power unit not only developed more output and a higher torque, it was also even more economical than the preceding two-valve units and set new standards for a prechamber engine in terms of pollutant emissions. EDC also played a decisive role in the 2.9 liter direct-injection diesel engine introduced in 1995. This 129 hp (95 kW) five-cylinder unit was some 18 percent more economical than a comparable prechamber engine. This also meant 18 percent lower carbon dioxide emissions as a result of reduced thermal losses during combustion. In conjunction with the adapted emission control system this also reduced emissions of hydrocarbons and particulates in the direct-injection engine by more than one fifth versus conventional prechamber diesels.

In 1997, a four-cylinder Mercedes-Benz power unit once again opened up a new chapter in the worldwide story of the car diesel engine. Its special feature was direct fuel injection using the common rail principle jointly developed by Daimler-Benz and Bosch. The magical acronym for this revolutionary advance is CDI, Common Rail Direct Injection, and is synonymous with high output, excellent torque characteristics at very low engine speeds, great fuel economy, minimal exhaust emissions and low noise.

In 2003, Mercedes-Benz became the first automobile brand in the world to offer the combination of particulate filter and EU 4 emission standard for diesel passenger cars. In 2005 Mercedes-Benz equipped all diesel cars with maintenance-free particulate filters as standard. As a result, in future 40 models from A- to S-Class get a particulate filter system which requires no additives and cuts emissions of soot particles by 95 percent.

In 2005, Mercedes-Benz introduced the new diesel technology BLUETEC. Using the Selective Catalytic Reduction (SCR) process it reduces nitrogen oxides in the exhaust gases of diesel engines by around 80 percent. To achieve this, the additive AdBlue is metered into the exhaust line. AdBlue, available at gas stations, is an aqueous urea solution which uses ammonia (NH3) as an intermediate product to form the natural, harmless products water and nitrogen from the nitrogen oxides in the catalytic converter. Mercedes-Benz planned to use the great potential of this technology for diesel passenger cars as well and began testing in 2005. The first series-produced passenger car featuring BLUETEC drive was presented the following year: The Mercedes-Benz E 320 BLUETEC was launched in October 2006 in the USA. In August 2007, the company announced the start of vehicle series production of the E 300 BLUETEC for the European market.

BLUETEC is a contribution to Mercedes-Benz’s goal of making diesel vehicles just as clean in their emissions as gasoline-powered vehicles, in preparation for future emissions standards worldwide. The company pursues a three-stage plan:

1. Changes in engine design proper to make combustion as efficient and clean as possible.

2. Oxidation catalysts to cut carbon monoxide and hydrocarbon emissions, and particulate filters to reduce particulate emissions to a hardly detectable level.

3. BLUETEC technology to reduce nitrogen oxides – the remaining component of the exhaust gases and still in excess of the levels attained by gasoline engines today – by 80 percent.

But Mercedes-Benz also points to the future of the diesel drive with research on the use of fuels manufactured from biomass. They include SunDiesel®, a synthetic fuel made from biomass. In contrast to diesel fuel obtained from oil seeds, SunDiesel® can be obtained from various organic substances, including waste wood. In 2003 Mercedes-Benz set up a SunDiesel® filling station on the premises of Stuttgart corporate headquarters for the purpose of testing the new fuel.

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