Heritage: Sights always set on alternatives
How long will oil reserves last? Are there better powertrains than the internal combustion engine? These issues are being discussed since the car was invented, at constantly changing intensity. The discussion is determined by economic, political and technical factors. The search for alternative powertrains was thus already an issue during the era of Benz & Cie. and Daimler-Motoren-Gesellschaft. It is also a constant presence for Mercedes-Benz vehicles.
Electric cars (since 1899)
The Motorfahrzeug- und Motorenfabrik Berlin AG Company, the precursor of the Mercedes-Benz Berlin plant, presented its first electric vehicle as early as 1898. Project partner of the "motor vehicle and engine factory" in Berlin-Marienfelde was American Columbia Electric Company based in Connecticut. The motor, whose battery was housed in the body of the car, sent its power to the rear axle via a gear drive. The "electric semi-coach" model weighed 1,800 kilograms, had a range of 40 kilometres, consumed 0.34 kilowatt hours per kilometre, managed inclines of up to seven percent, and cost 9,300 marks.
The first electrically powered Mercedes was built in 1907. A contemporary report about the motor show in Vienna in spring 1907 had this to say: "The elegance of the electric urban vehicle is perfectly illustrated by several Mercedes-Electriques, which were very well received at the exhibition." Mercedes-Electrique vehicles were used in particular as fire engines and buses. The advantages included that they were always ready to start promptly, and were relatively cheap to run, because mechanical components such as transmission, clutch or chains were no longer needed to transfer the power, thanks to electric wheel hub motors.
In 1908, the Berlin fire brigade, for example, also opted for electric vehicles when a new fire company comprising four Mercedes-Electrique vehicles was put into service (gas pumper truck, steam pumper truck, water tender and turntable ladder truck).
The first concept for a modern electrically powered van at Mercedes-Benz was created in 1972 - the LE 306. The engine developed 31 kW (42 hp), achieved a maximum speed of 70 km/h, and had a range of 65 kilometres. The LE 306 was also used at the 1972 Olympic Games in Munich. In the years that followed, a total of 89 electric vans collectively clocked up some 2.9 million kilometres in test drives.
In early 1982, Mercedes-Benz began testing the electric powertrain for passenger cars. The research car based on a 123-series estate model had a novel powertrain concept. A single module comprised a DC drive motor (continuous output 25 kW/34 hp, peak output 32 kW/44 hp), a multi-disc start-off clutch, an automatic transmission (derived from a passenger car automatic transmission), an upstream two-cylinder internal combustion engine (10 kW/14 hp) with noise encapsulation for emergency power, and an in-line centrifugal clutch. The modified load compartment housed a newly designed nickel-iron battery. The vehicle had a range of about 100 kilometres.
A Mercedes-Benz 190 (201 series) was the basis for another electric test car that was presented to the public in 1991. Two electric motors excited by permanent magnets, each with a peak output of 16 kW (22 hp), drove the rear axle directly. Due to the high torque across the entire rev range, no transmission was needed. This meant that the drivetrain and the losses it entails could be eliminated. The compact and lightweight design created space and saved on weight. However, this solution was more expensive than a conventional DC motor. Under the bonnet of this “laboratory on wheels” was a lot of electronic equipment for controlling the powertrain, and a battery. A second battery and measuring instruments took up almost the entire boot.
In 1992, a four-year demonstration project started on the island of Rügen to test the latest generation of electric vehicles and gain information about their performance under real-life conditions. All in all, 60 passenger cars and vans from various manufacturers participated in the project. Mercedes-Benz supplied ten further advanced 190 models and ten likewise improved MB 100 vans with different kinds of combinations of electric motor and battery. The vehicles were charged at standard power outlets and also at special charging stations, where electricity was generated in part directly from sunlight.
At the 1992 Olympic Games in Barcelona, the MB 100 E was used as a support and transport vehicle. It was fitted with a DC shunt wound motor, producing 28 kW (38 hp) and enabling a top speed of 80 km/h with a maximum range of 80 kilometres.
Testing of electric powertrains continued. A prototype based on the C-Class (202 series) powered by an asynchronous electric motor (35 kW/48 hp) was built in 1993. Zebra high-energy batteries from AEG gave the concept car a range of 110 kilometres. The engineers accommodated all the technology in the car so skilfully that the electrically powered Mercedes-Benz offered almost the same space as a standard C-Class Saloon. The payload capacity was still as high as 370 kilograms. The safety level was identical to that of a production C-Class.
In 2006, a pilot project of the smart brand was launched in the UK. Electric smart cars started daily operations there in November that year. The company provided approximately 100 vehicles for lease to selected British customers. The car was powered by an electric motor with an output of 30 kW (41 hp). It was the starting shot for the electric success story at smart – please see corresponding chapter.
In 2012, Mercedes-AMG started a new era with the SLS AMG Coupé Electric Drive: The locally emission-free super sports car featuring hi-tech from Formula 1 racing represented the most exclusive and dynamic form of electric motoring. The most powerful AMG high-performance vehicle was equipped with four electric motors with a system output of 552 kW and a peak torque of 1000 Nm, making the gullwing the world's fastest electrically powered production vehicle: The SLS AMG Coupé Electric Drive accelerated from zero to 100 km/h in 3.9 seconds.
The first B-Class Electric Drive came off the assembly lines at the Mercedes-Benz Rastatt plant in November 2014. This marked the first time that Mercedes-Benz models with internal combustion engine and electric powertrain were built on one and the same assembly line. The B-Class Electric Drive is based on the front-wheel-drive architecture of the new Mercedes-Benz compact car generation and makes use of the modular component system. The batteries are housed safely in the underbody of the vehicle (ENERGY SPACE).
Since 2017 the new smart electric drive has been making the world of electric mobility a more attractive proposition than ever. This is because it combines the agility of the smart with locally emission-free driving – the ideal combination for urban mobility. The smart fortwo coupé and smart forfour (electrical consumption, combined: 12.9/13.1 kWh/100 km; CO2 emissions, combined: 0 g/km) were followed in the summer of 2017 by the likewise battery-electric-powered smart fortwo cabrio (electrical consumption, combined: 13.0 kWh/100 km; CO2 emissions, combined: 0 g/km). With 160 newton metres of torque, available right from the start, the 60 kW electric model offers remarkably agile acceleration. A fully charged battery gives it a range that is more than adequate for driving in city traffic.
Hybrid powertrains (since 1907)
Hybrid powertrains, especially the combination of electric motor and internal combustion engine, are an important option for future motor vehicles. Mercedes-Benz has been conducting research in this field continuously since 1969. However, the tradition of hybrid powertrains dates back even farther in the history of the brand: Daimler Motorengesellschaft Wiener Neustadt presented a Mercedes-Mixte developed by Ferdinand Porsche as early as in 1907. Hybrid models of various passenger and commercial vehicles followed. Hybrid powertrains continued to be used until the first quarter of the 20th century.
In 1969, the OE 302 hybrid bus marked a new start for hybrid research. In the years that followed, (for the first time in a passenger vehicle in the electric estate model of the 123 series, see above), more than 20 concept and research vehicles with hybrid powertrains were built in all vehicle categories from the smart HyPer sub-compact car to the Atego truck. In 2005, Mercedes-Benz first presented an S-Class with hybrid powertrain at the North American International Auto Show in Detroit. At the 2005 International Motor Show (IAA) in Frankfurt, two more concept vehicles based on the new V 221 S-Class were then on display: the DIRECT HYBRID with petrol engine and electric motor, and the BLUETEC HYBRID, which combined a diesel engine with an electric motor. The electric motor of both concept vehicles produced 6 kW (8.2 hp). It was used as a starter motor and a start-off booster, and was also able to function as a generator for converting kinetic energy into electricity.
With 20,000 buyers worldwide, the production S 400 HYBRID became a success from more than just a technical standpoint starting in 2009. It consumed just 6.3 litres of fuel per 100 kilometres (combined) in the NEDC. This represented a reduction of 20 percent over the predecessor. CO2 emissions of 147 grams per kilometre were also a record in this vehicle segment. These exemplary figures went hand in hand with outstanding performance: the petrol engine develops 225 kW (306 hp), while the electric motor adds another 20 kW (27 hp). The internal combustion engine's peak torque of 370 Nm was supplemented with another 250 Nm from the electric motor.
In 2013, Mercedes-Benz launched the S 300 BlueTEC HYBRID, which combined the 2.2-litre four-cylinder diesel engine rated at 150 kW (204 hp) with a powerful hybrid module developing 20 kW (27 hp). The peak torque of 500 Nm produced by the internal combustion engine was boosted by 250 Nm of peak torque generated by the electric motor. The S 300 BlueTEC HYBRID made do with 4.4 litres per 100 km in the combined cycle (CO2: 115 g/km), and complied with the criteria for energy efficiency class A+. Consequently, Mercedes-Benz cut fuel consumption in the 150 kW performance class by nearly half over the course of ten years.
The S 500 PLUG-IN HYBRID was another milestone in 2014. It offered a system output of 325 kW with 650 Nm of torque, accelerated from 0 to 100 km/h in just 5.2 seconds and had an all-electric range of up to 33 km. The certified consumption is 2.8 litres/100 km, which is equivalent to emissions of 65 g CO2/km. Key elements of this impressive output are the V6 biturbo and the intelligent hybrid drive. Its new high-voltage lithium-ion battery with an energy content of 8.7 kWh could be externally recharged via a charging socket in the right side of the rear bumper.
Enhanced range and performance are offered by the S 560 e displayed at the 2017 International Motor Show (IAA) in Frankfurt (fuel consumption, combined: 2.1 l/100 km, CO2 emissions, combined: 49 g/km, weighted power consumption: 15.5 kWh/100 km), a plug-in hybrid of the latest generation. This model can travel around 50 kilometres in all-electric mode. A crucial factor here is that, although the battery size remains unchanged, the new lithium-ion battery has an increased rated capacity of 13.5 kWh. Evolving the cell chemistry from lithium-iron-phosphate (LiFePo) to lithium-nickel-manganese-cobalt (Li-NMC) allowed the cell capacity to be increased from 22 to 37 Ah.
Developed together with Bosch as part of the EM-motive joint venture, the electric motor was specially designed for the 9G-TRONIC plug-in hybrid transmission. The new, significantly enhanced power electronics have allowed further increases in output and torque. The electric output of 90 kW and 440 Nm contributes to the effortlessly superior driving sensation in the S-Class.
Also making its debut in series production of the S-Class in 2017 is the 48-volt on-board electrical system. The new six-cylinder in-line petrol engine features further trendsetting technologies such as the integrated starter-alternator and the electric booster compressor.
All milestones of the hybrid powertrain at a glance:
- 1982: Mercedes-Benz concept with two-cylinder horizontally opposed engine
- 1993: Mercedes-Benz "Taxi Hybrid" as first parallel hybrid. A C-Class combined a 55 kW (75 hp) four-cylinder diesel engine with an electric motor that had an output of 20 kW (27 hp).
- 2001: smart fortwo cdi. A 20 kW (27 hp) electric motor in concert with the 30 kW (41 hp) three-cylinder diesel engine formed a highly space-saving unit.
- 2002: Mercedes-Benz Unimog "E-Drive"
- 2002: Mercedes-Benz M-Class "HyPer". ML 270 CDI with a 120 kW (163 hp) common-rail diesel engine and automated manual transmission. It featured an electric motor with an output of 45 kW (61 hp) and high torque, installed between the diesel engine and the transmission.
- 2003: Mercedes-Benz F 500 Mind. The four-litre V-8 diesel engine produced 178 kW (242 hp) of power and 560 Nm of torque. The electric motor added another 48 kW (65 hp) and 300 Nm. The company featured the same powertrain in the Mercedes-Benz Vision Grand Sports Tourer concept vehicle.
- 2004: Mercedes-Benz Sprinter with plug-in-hybrid powertrain
- 2005: Mercedes-Benz S-Class "Hybrid". Eight-cylinder diesel engine producing 191 kW (260 hp) of power and 560 Nm of torque, plus two electric motors with a total output of 50 kW (68 hp).
- 2005: smart crosstown. Hybrid with three-cylinder petrol engine (45 kW) and electric motor (23 kW)
Production cars (hybrid and electric drive)
- 2009: S 400 HYBRID (20,000 buyers worldwide)
- 2009: ML 450 HYBRID
- 2012: smart electric drive
- 2012: E 300 BlueTEC HYBRID
- 2012: E 400 HYBRID
- 2013: SLS AMG Coupé Electric Drive
- 2013: S 400 HYBRID
- 2013: S 300 BlueTEC HYBRID
- 2014: C 300 BlueTEC Hybrid
- 2014: B-Class Electric Drive
- 2014: S 500 PLUG-IN HYBRID
- 2015: C 300 e
- 2015: GLE 500 e
- 2017: S 560 e
- 2017: S 450 and S 500 with 48-volt on-board electrical system
Fuel cell cars (since 1994)
The first fuel-cell-powered vehicle in the world, with which the Daimler-Benz researchers demonstrated the viability of the fuel cell for powering a vehicle in 1994, went by the name NECAR 1 ("New Electric Car"). The experimental vehicle, a Mercedes-Benz van, resembled a laboratory on wheels: The load compartment was filled with 800 kilograms of the still voluminous fuel cell system and small hydrogen tank. NECAR 2, a Mercedes-Benz V-Class with integrated fuel-cell power unit under the short bonnet, hit the road as early as in 1996. The six seats were reserved for the occupants. The hydrogen tanks were mounted on the roof. The vehicle reached a top speed of 110 km/h and had a range of around 250 kilometres.
NECAR 4 was a zero-emission vehicle (ZEV) for operating purely on hydrogen. The vehicle based on an A-Class offered room for five people plus luggage. The liquid hydrogen was carried in a cylindrical tank in the rear. It had a range of up to 450 kilometres and a top speed of 145 km/h. As NECAR 4 emitted no exhaust gases whatsoever, this vehicle already met the future requirements of the US state of California as far back as 1999. Number 4 represented a crucial step on the road to production readiness. A variant of NECAR 4, equipped with even more advanced technology and three tanks with compressed hydrogen in the rear, was also used for practical testing in California, where intensive field and road tests under real-life conditions were conducted with a total of 15 vehicles up until 2003.
NEBUS, the "New Electric Bus" presented in 1997, represented the transfer of the fuel cell technology to the commercial vehicle sector by Mercedes-Benz. The hydrogen was stored in seven glass-fibre-encased aluminium tanks on the roof. One full tank was enough for a range of 250 kilometres, sufficient for the daily workload of a bus in line service. In 2003, the first 30 urban buses with fuel cell powertrain went into operation in certain large European cities, followed by more buses all around the world.
In 2005, Mercedes-Benz presented the F 600 HYGENIUS research vehicle at the 39th Tokyo Motor Show. The new fuel cell was 40 percent smaller than previous systems, but also significantly more efficient and powerful: the system delivered 85 kW (115 hp).
The fuel cell powertrain finally went into (small) series production in 2010. Produced under series production conditions, the Mercedes-Benz B-Class F CELL has since been in day-to-day operations with customers on the European and American markets. The total distance covered by the Daimler fuel cell fleet, which with the inclusion of a host of research vehicles now numbers more than 300 vehicles, has in the meantime reached the twelve million kilometre mark. The 70-strong F-CELL fleet in the USA alone has covered a total of 3.2 million kilometres (2 million miles).
In 2011, Mercedes-Benz presented the F 125! research vehicle as the highlight of the 125th anniversary of the motor car. The concept of a four-seat luxury saloon combined cutting-edge, high-efficiency storage, powertrain and bodywork technologies with unique operating and display concepts. At the heart of the powertrain was an especially powerful further development of the fuel cell system from Mercedes-Benz, in combination with the plug-in technology. Other highlights were lighter and more efficient energy storage units based on lithium-sulphur technology and the so-called "structurally integrated hydrogen composite storage system", which integrated the hydrogen tanks fully into the body structure. Four powerful electric motors positioned near the wheels delivered sporty and superior driving performance.
The powertrain of the F 125! was further advanced in the F 015 Luxury in Motion (2015) research vehicle. The fuel cell stack was further optimised in terms of performance, efficiency and durability, and delivered the traction current for two electric motors, each with an output of 100 kW (136 hp). These are installed in a compact arrangement in the rear end of the vehicle and channel their power to the rear wheels. The electrical powertrain generates a total peak output of 200 kW (272 hp). The electric hybrid system has a total range of 1,100 kilometres, of which some 200 kilometres can be driven on the especially powerful and compact high-voltage battery, and around 900 kilometres on the electricity produced in the fuel cell. The design provides for the use of CFRP pressure tanks for hydrogen storage.
In 2017 at the IAA International Motor Show in Frankfurt, Mercedes-Benz presented preproduction models of the new Mercedes-Benz GLC F-CELL as the next milestone on the road to emission-free motoring. For the first time anywhere in the world, the innovative fuel cell and battery technology are combined here in a plug-in hybrid: in addition to hydrogen, the all-electric variant of the popular SUV will also run on electricity. The intelligent interplay between battery and fuel cell, along with short refuelling times, will in future make the GLC F-CELL a vehicle of high everyday practicality that is also suitable for long-distance motoring.