Another world champion for low CO₂ emissions at the Mercedes-Benz IAA stand was the ML 450 HYBRID, which will be launched on the market in 2009 as the world’s most economical gasoline hybrid in the SUV class. The vehicle’s innovative two-mode system allows it to be operated even in different types of driving situations in a pure electric mode that meets the highest comfort requirements.

In the two-mode system, a combustion engine and a transmission work with two electric motors in such a manner as to ensure that the overall drive system always achieves an optimum level of fuel consumption. In other words, two-mode vehicles require relatively little fuel, regardless of whether they’re in stop-and-go traffic or on highways.

The new two-mode concept in the ML 450 HYBRID allows for the use of two compact permanent-magnet electric motors that take up much less space than comparable systems. The two cooled electric motors are located inside the transmission, whose compact design can only truly be seen in an x-ray image. The latter reveals that alongside the two electric motors, the transmission, which is directly flanged to the crankcase, also houses three planetary gear sets, four wet clutches, a hydraulic module, and an electric oil pump.

Versatile transmission

Thanks to the clever interplay between the transmission components and the electronic motor and transmission control system, a number of features can be varied. For example, the vehicle has two continuously variable electric modes for city and highway driving, four different speeds, and a continuously variable gear ratio. This unique system combines the benefits of a conventional automatic transmission with those of a continuously variable transmission.

As a result, the drive system in the ML 450 HYBRID can operate extremely smoothly like a conventional continuously variable transmission, while still allowing for complete hybrid functionality. In addition, the system can automatically select specific gears in accordance with the situation so as to ensure optimal output and fuel consumption. Power is transmitted to the wheels by a conventional mechanical all-wheel drive ?system.

SUV with all hybrid functions

Electricity is supplied to the two electric motors by a 288-volt battery that can store a large amount of energy. The ML 450 HYBRID’s intelligent energy management system enables the vehicle to offer all the features that make a hybrid a hybrid: pure electric driving, start/stop function, booster effect when the electric motor supports the combustion engine, and brake energy recovery and storage.

Andreas Truckenbrodt, head of the Hybrid Project Center, describes the benefits of the two-mode technology as follows: “The innovative overall concept employed in the ML 450 HYBRID has enabled us to achieve a new level of hybridization quality in a vehicle of this class. As a result, Mercedes-Benz can offer a hybrid technology that guarantees low fuel consumption, the highest levels of comfort, and a completely usable trunk area. The two-mode hybrid system also improves fuel consumption at high speeds — a feature that gives it a further advantage over other hybrid concepts on the market”.

For city and highway driving
Der ML 450 HYBRID bietet als Vollhybrid Start-Stopp-Funktion, Rekuperation, Boost-Effekt und rein elektrisches Fahren.
Engine:
Gasoline engine	V6
Rated output	205 kW / 279 hp
Max. torque	338 Nm
Hybrid module:
Type	Two-mode with two electric motors
Max. torque	260/270 Nm
Overall drive system:
Combined max. torque	480 Nm
Overall fuel consumption:
Consumption (NEDC)	7.7 l/100 km
CO2 emissions	185 g/km