In 1892 Rudolf Diesel applies for a patent for his engine, which is granted on 23 February 1893 as DRP 67 207 “ on a principle of operation and construction for internal combustion engines.” He gets the first successful prototype of a production-standard diesel engine running in 1897. In the cylinder of a diesel engine, fuel is mixed with appreciably more air than in a petrol-powered engine. This makes for very efficient combustion. In addition, the diesel engines require no sparkplugs since diesel fuel with its very good ignition qualities, or rather the air-fuel mixture, ignites spontaneously owing to the very high compression ratio – this is why it is also called the compression-ignition engine. Ignition is triggered off by the sharp rise in temperature during the compression stroke of the piston.

At the Deutz company, Prosper L’Orange develops an injection pump for diesel engines and enlarges the combustion chamber with an afterchamber to improve mixture formation. In 1908 he submits a patent application for the afterchamber diesel engine.

In experiments which he carries out as head of engine testing at Benz & Cie., L’Orange further improves his engine. A new cylinder head shape with a hemispherical chamber now takes the place of the afterchamber. In this so-called prechamber, following injection a small portion of the diesel fuel burns, generating high pressure and propelling the remaining diesel-air mixture into the cylinder where it gets swirled. The pressure and the mixing action permit rapid combustion at high temperatures and thus higher engine speeds. On 14 March 1909, L’Orange files a patent application (DRP 230 517) for the prechamber system.

Prosper L’Orange changes the shape of his prechamber in 1919 by using a funnel-shaped insert to set it off more clearly from the combustion chamber proper. This way he achieves reliable ignition and good combustion under different loads. He takes out a patent on it on 18 March 1919 (DRP 397 142).

Parallel to the funnel prechamber, L’Orange designs a new injection nozzle for more reliable introduction of fuel into the cylinder.

The variable injection pump permits infinite variation of the delivered quantity of fuel, thus enabling precision control of power delivery. The injection pump introduced in 1921 is the last vital component developed by L’Orange for the first diesel engine to see use in vehicles.

The S6 farm tractor, featuring an 18 kW (25 hp) two-cylinder prechamber diesel with a rated speed of 800 rpm, serves to launch the diesel’s career as a vehicle drive.

The first of three prototypes of the OB2 truck diesel engine is running on a test bench as early as September 1922. In October Benz installs the four-cylinder into a 5 K 3 chassis, and in spring 1923 the decision is made to produce it: the world’s first diesel truck develops 33 – 37 kW (45 - 50 hp) at 1000 rpm.

In competition to L’Orange’s prechamber diesel, Daimler-Motoren-Gesellschaft (DMG) develops an air-injection diesel engine for its trucks. This unit is based on experience gained from the manufacture of submarine diesel engines employing the air injection principle.

The injection pump introduced by Robert Bosch for diesel engines in 1927 is systematically improved as against older systems. With this injection pump, Bosch, himself one of the first buyers of a diesel truck in 1924, greatly furthers the acceptance of the diesel drive.

A new Mercedes-Benz single-cylinder diesel engine is first used in the OE tractor.

The compact OM 59 prechamber diesel powers the new Lo 2000 express truck.

The 10,000th Mercedes-Benz commercial vehicle with diesel engine is built in Gaggenau in 1935.

The Mercedes-Benz 260 D is the world’s first diesel passenger car. It is equipped with the OM 138 engine, developed from a truck diesel. The unit has four cylinders, a displacement of 2.6 litres and an output of 33 kW (45 hp).

Mercedes-Benz begins developing the new 300 engine series for commercial vehicles during the Second World War.

The six-cylinder in-line OM 312 is the first representative of the new series, debuting in 1949. The 300 engine family in the commercial vehicles of Mercedes-Benz extends its career into the new millennium.

In a fire engine, in 1953 Mercedes-Benz presents its first turbocharged production diesel engine. Its output is about 25 percent higher than that of a naturally aspirated engine.

The OM 352 is the first diesel engine for Mercedes-Benz commercial vehicles to have direct injection. The economical and performance-enhancing injection system with four-hole nozzle quickly becomes generally accepted in trucks and other commercial vehicles.

To attain higher outputs for fuel-injected diesel engines in commercial vehicles, Mercedes-Benz offers the OM 352 A engine with exhaust-gas turbocharger for the first time in 1966.

In Mannheim Mercedes-Benz build their 100,000th diesel engine for commercial vehicles in 1969.

Mercedes-Benz introduces the new 400 engine series for heavy-duty commercial vehicles in 1970. The first is a V10, which is joined later by V8, V6 and six-cylinder in-line units.

The five-cylinder in-line OM 617 with a displacement of 3005 cubic centimetres is the first five-cylinder diesel engine in the world to be used in a passenger car. The engine premieres in the Mercedes-Benz 240 D 3.0 (W 115 series).

In the 300 SD S-Class model, Mercedes-Benz presents a diesel engine with exhaust-gas turbocharger for the first time. With an output of 85 kW (115 hp) and torque of 250 Newton metres, the 300 SD is offered exclusively for the US market. The 300 T Turbodiesel as turbocharged diesel model which is also sold in Europe does not follow until 1980.

In 1980, Mercedes-Benz introduces intercooling (charge air cooling) to complement the turbocharger in the new OM 422 AL engine for heavy-duty trucks. Cooling results in more oxygen in the intake air and in higher power output during combustion.

In the diesel models of the compact class launched in 1982 (W 201 series), the engine is fully encapsulated for the first time. This reduces the noise produced by the drive system by about half. Colloquially, the engine design is dubbed the “whisper diesel.”

In 1985, Mercedes-Benz is the first automotive brand in the world to supply diesel saloons with a particulate filter system as an optional extra to California. The experience gained from this programme is the basis for developing new filter technologies.

In 1989, Mercedes-Benz presents revised engines which cut particulate emissions by around 40 percent. Their features include a new prechamber with oblique fuel injection, which enables more efficient combustion. The diesel technology improvement programme under which these engines are developed is called the “Diesel ’89” initiative.

The exhaust gases of a diesel engine are markedly different from those of a petrol-fired engine. While the diesel engine gives off less carbon dioxide, its exhaust gas contains a higher proportion of nitrogen oxides. In 1991 Mercedes-Benz reduces these pollutants with an emission control system employing exhaust-gas recirculation and an oxidising catalytic converter. This combination lowers the temperature in the combustion chamber and reduces the formation of nitrogen oxides by about 70 percent. Initially offered as an optional extra, the emission control system becomes standard equipment in 1993.

Four-valve technology arrives in the diesel segment in 1993 when Mercedes-Benz introduces the first car diesel engine with four valves per cylinder and electronic control. Four-valve technology gives the diesel engine higher power and better economy than the previous two-valve design. Electronic Diesel Control (EDC) sees use in production vehicles beginning in 1995 when Mercedes-Benz introduces the direct-injection diesel engine with 2.9 litres displacement.

Two new engine series for commercial vehicles are introduced at once by
Mercedes-Benz in 1996. The OM 500 diesel V-engines operate in the new heavy-duty Actros truck; the OM 900 in-line engine generation is used in the light-duty Atego truck.

The CDI age begins in 1997. The acronym stands for “Common Rail Direct Injection.” Developed by Daimler-Benz in cooperation with Bosch, this direct fuel injection system works with a common fuel line (common rail). Whereas conventional direct injection engines build up pressure for every injection operation anew, in the common rail high pressure is permanently generated, enabling the fuel to be forced to the variable and very precisely controlled injection nozzles at a pressure of up to 1350 bar. CDI makes the diesel engine a model of high performance, excellent torque already in the lower rev range, great fuel economy, minimal pollutant emissions, and generation of little noise.

The Mercedes-Benz Cito is an innovative midibus with a diesel-electric drive in which an OM 904 LA diesel engine powers a generator which supplies energy to the electric traction motor.

The second generation of CDI technology in 2002 once again improves performance, consumption, comfort and emissions. To achieve this, among other things the Mercedes-Benz engineers raise the ignition pressure from 145 bar to 155 bar to optimise the gas cycle. The result is greater pulling power and flexibility. The injection pressure of now 1600 bar, in conjunction with the newly developed seven-hole injection nozzle, permits finer distribution of the fuel in the combustion chambers, better mixture formation, and more homogeneous combustion.

As first harbinger of BlueTec, an AdBlue® filling station is opened in Stuttgart in 2003. AdBlue® (“Additive Blue”) – an aqueous urea solution – is injected into the exhaust-gas flow in the SCR (Selective Catalytic Reduction) process. A catalytic converter then reduces the nitrogen oxides in the pretreated exhaust gas to nitrogen and water vapour. SCR is part of the BlueTec system for uncompromising reduction of diesel emissions. From 2005, step by step DaimlerChrysler changes over the entire truck and bus range so that the vehicles comply with the Euro 4 and Euro 5 standards.

In 2003 Mercedes-Benz introduces maintenance-free particulate filters for diesel engines. Initially the filters are optional equipment. In the summer of 2005, more than 30 car models of Mercedes-Benz, from the A-Class to the S-Class, are fitted with a particulate filter as standard. In autumn 2005, the manufacture of retrofit kits for vehicles produced before this breakpoint begins, initially for the C and E-Class.

In 2003 the F 500 Mind research car presents a hybrid drive combining a V8 diesel engine with an electric motor. The diesel attains an output of 184 kW (250 hp) and maximum torque of 560 Newton metres, and the electric motor adds another 50 kW (68 hp) and 300 Newton metres maximum torque. Electronic control of the link between the two drive units lets each bring its specific advantages into play. Whereas the electric motor can move the car on its own for starting off, parking and slow-speed driving, the strong diesel engine is engaged when more power is required. The union of the two drive systems demonstrates its value particularly in urban traffic.

In the Vision Grand Sports Tourer 2 in 2004 Mercedes-Benz also shows a diesel hybrid drive. The V8 diesel with four litres displacement and 184 kW (250 hp) is again coupled with a 50-kW (68-hp) electric motor. In 2005 the S-Class HYBRID (NAIAS in Detroit) and the S-Class BlueTEC HYBRID (International Motor Show in Frankfurt am Main) follow. To further develop such combinations of internal combustion engines and electric motors, the company cooperates with General Motors and the BMW Group; the three enter into an alliance in September 2005. The objective of research is formulated in a Memorandum of Understanding on the joint development of the hybrid drive.

In 2004 Mercedes-Benz introduces trucks with OM 500 engines and BlueTec technology for emission control. These vehicles meet the especially stringent Euro 4 and Euro 5 emissions norms. As early as February 2006, delivery of the 10,000th BlueTec truck with Euro 5 engine takes place.

A new high-tech V6 diesel engine marks the beginning of the third generation of CDI technology at Mercedes-Benz. Owing to new materials and optimisation of the entire unit, the new CDI engines attain even higher combustion pressures than before – the engineers aim at up to 200 bar and intend to boost the injection pressure too in future, to as high as 2000 bar. In addition, the complex CDI technology is further refined. The fuel is no longer injected all at once, but in as many as five portions. Special actuators (piezo crystals) take over the control of the injection nozzles: with electric pulses the atomic structure of the crystals can be expanded several hundred thousand times per second if required. With this sophisticated injection system, not only are the emissions further reduced; the working noise of the engine is also diminished once more.

In 2006, Mercedes-Benz introduces BlueTEC for passenger cars to the market in an
E-Class. The technology for the cleanest diesel in the world has been successfully used in commercial vehicles since 2005. The Mercedes-Benz E 320 BlueTEC is the first representative of a new generation of diesel cars of the Stuttgart brand on this technical basis. From autumn 2006 the E 320 BlueTEC goes to market in the USA; the market launch in Europe is scheduled for 2008.

Under development since 2002, the BlueTEC (written BlueTec for commercial vehicles) modular technology package relies on several means of reducing diesel emissions. On the one hand, these include familiar methods like the oxidising catalytic converter and particulate filter, along with optimised engines. But the heart of the system is the actual BlueTEC technology for nitrogen oxide reduction. In the first production car equipped with it, the E 320 BlueTEC, there is a complex catalytic converter system consisting of an improved nitrogen-oxide storage-type catalytic converter and an SCR catalytic converter. In normal operation the nitrogen oxides in the exhaust gas are collected in this catalytic circuit. Regular adjustments to the air-fuel mixture in the engine change combustion, and with it the composition of the exhaust gases, for a brief period. In the process, BlueTEC separates the stored nitrogen oxides into nitrogen and water vapour.

More complex, but more effective still is Selective Catalytic Reduction (SCR) by means of AdBlue® injection. When AdBlue® is injected into the pretreated exhaust gas, ammonia is released which then causes reduction of nitrogen oxides to harmless nitrogen and water in the downstream SCR catalytic converter. Spraying this aqueous urea solution into the exhaust-gas flow is currently the most efficient method of exhaust-gas aftertreatment for diesel engines. This system can reduce nitrogen oxides by as much as 80 percent. With the Vision GL 320 BlueTEC, Mercedes-Benz engineers demonstrate in 2006 that this too is a process that can find use in large-scale production. In autumn 2006, the E 320 BlueTEC production car finally appears.

BlueTec technology has been very successfully employed in Mercedes-Benz commercial vehicles in Europe since 2005. In the meantime this technology has performed outstandingly in more than 20,000 Actros, Axor and Atego trucks. BlueTec cuts nitrogen oxides so sharply that the emissions limits applicable to trucks from 2009 are already undercut today. This is rewarded with lower road tolls for trucks with Euro 5 technology through 2009. Whereas AdBlue® for cars might be replenished during a service stop, a comprehensive network of AdBlue® filling pumps for commercial vehicles is available in Europe.

At the end of 2007 Mercedes-Benz introduces the E 300 BlueTEC of the 211 series as first BlueTEC car for the European market. It is far and away the cleanest diesel in its class and fully complies with the EU5 emission standards.

Simultaneously, Mercedes-Benz speeds up the expansion of its line-up of BlueTEC vehicles in 2007. In Detroit, the three models R 320 BlueTEC, ML 320 BlueTEC and GL 320 BlueTEC are introduced; they will come onto the American market in 2008. The engineers provide a glimpse of the future at the Geneva Motor Show where they present the Mercedes-Benz Vision C 220 BlueTEC. The study car is the first to feature a four-cylinder engine with BlueTEC technology.

BlueEFFICIENCY, the comprehensive vehicle fuel consumption reduction programme, is introduced by Mercedes-Benz in 2008. The diesel engine in the CDI BlueEFFICIENCY models also profits from this innovative approach: for BlueEFFICIENCY the Mercedes-Benz engineers make use of the potential in all areas of development in order to reduce weight, wind resistance and rolling resistance further and organise the energy management of vehicles still more efficiently.

Since September 2009 Mercedes-Benz has been offering its complete BlueTEC model range also in Europe: along with the new W 212 series E-Class Saloon E 350 BlueTEC, the ML 350 BlueTEC 4MATIC, GL 350 BlueTEC 4MATIC and R 350 BlueTEC 4MATIC, which had already been on sale in the USA for a year. In spring 2010 the
G 350 BlueTEC followed. And so a genuine classic – the G-Class, a success for 31 years – meets the particularly clean 21st century Mercedes-Benz diesel drive.

The E 250 BlueTEC study designed for the North American market shows in spring 2009 how the BlueTEC technology of the E-Class can be combined with a four-cylinder with optimised fuel consumption. For this purpose an all-new four-cylinder diesel was combined with BlueTEC. The result is the most economical and cleanest diesel model in this vehicle category which, with its range of as much as 44 miles per gallon (equivalent to 5.3 litres per 100 kilometres), attains a fuel efficiency better than that of most hybrid vehicles in the US market.

The fourth generation of the common-rail direct-injection system premieres in the new generation of four-cylinder diesel engines in 2009. Its hallmark is a 400-bar increase in the maximum rail pressure, which now stands at 2000 bar. Newly developed piezo injectors are among the key components of the latest CDI engine generation. In contrast to the systems commonly used to date, this lift activates the nozzle needle directly, so that the fuel injection can be adjusted even more precisely in line with the current load and engine-speed situation – for example by means of precise multiple injections, which have a favourable effect on emissions, fuel consumption and combustion noise.

In the new diesel engines for the E 220 CDI BlueEFFICIENCY and E 250 CDI BlueEFFICIENCY, for the first time in series-built passenger car diesel engines Mercedes-Benz also realises two-stage turbocharging. The aim is to achieve further improvements, for example, in start-up performance and peak output, versus the single-stage turbocharger.

In summer 2010 Mercedes-Benz includes the first BlueTEC model of the S-Class in its range, the S 350 BlueTEC. It has combined fuel consumption of just 6.8 litres of diesel per 100 kilometres (NEDC), corresponding to CO2 emissions of 177 grams per kilometre. The S 350 BlueTEC already complies with the emission levels which are planned for 2014 with the introduction of the EU6 standard.

In autumn 2010 the S 250 CDI BlueEFFICIENCY follows. This S-Class Saloon is the first 5-litre car in the luxury class and the first model with a four-cylinder in the more than 60-year success story of the S-Class. The highly efficient turbodiesel achieves fuel consumption of only 5.7 litres per 100 kilometres in the NEDC cycle, which equates to CO2 emissions of 149 grams per kilometre. This makes the new S 250 CDI BlueEFFICIENCY the first vehicle in its class to undercut the 150 gram mark for CO2 emissions.

In 2011 the E 300 BlueTEC HYBRID comes onto the market. This first series-produced diesel hybrid passenger car of a European manufacturer will be available as Saloon and Estate. Presented at the Geneva Motor Show in 2010, the vehicle pairs a 2.2-litre four-cylinder diesel engine developing 150 kW (204 hp) with a powerful hybrid module with 15-kW electric motor. The electric motor, positioned between the internal combustion engine and the seven-speed automatic transmission, assists the diesel engine when the car is accelerating (boost effect), although it is also suitable for driving using electric power alone. It is also used for the recuperation of braking energy in alternator mode. The E 300 BlueTEC HYBRID consumes 4.1 litres of diesel fuel per 100 kilometres. This corresponds to CO2 emissions of 109 grams per kilometre.