It had the capacity to travel up to 30 km powered exclusively by electricity, thus creating no local emissions. Thanks to its efficient drive system and the carbon dioxide bonus for battery electric powered operation it achieved a certified consumption level of just 3.2 litres of petrol fuel per 100 kilometres. With carbon dioxide emissions of only 74 grams per kilometre in the NEDC (New European Driving Cycle), the experimental vehicle demonstrated the future-compatibility of coming S-Class generations. These exceptional levels were achieved thanks to the combination of a plug-in hybrid drive system with efficiency-enhancing BlueEFFICIENCY measures.

At the same time, the Vision S 500 plug-in HYBRID featured all the typical strong points of the Mercedes-Benz S-Class: top-level comfort, exceptional safety and effortlessly superior performance. The concept vehicle’s drive system consisted of three main components: a powerful V6 internal combustion engine featuring next-generation direct injection, a hybrid module delivering 44 kW (60 hp), and a lithium-ion battery with over 10 kWh storage capacity, which could be recharged at a charging station. The vehicle was able to accelerate to 100 km/h from a standstill in 5.5 seconds.

The electrical drive system components demonstrated the versatility of the Mercedes-Benz scaleable hybrid drive system modular principle. In its design, the hybrid module presented only minor differences from the 15 kW electric motor with which the S 400 HYBRID was equipped, although it was three times as powerful as the latter. For this reason it was possible to integrate it elegantly in the housing of the 7-speed 7G-TRONIC automatic transmission. This hybrid variant left the generous interior of the experimental vehicle intact, as did the S 400 HYBRID – an important guide for future model generations.

Enlarge   Mercedes-Benz Vision S 500 Plug-in HYBRID, concept vehicle for a “Three-litre-per-100-km” luxury class car with a consumption of only 3.2 litres of petrol per 100 kilometres.     Whereas the extremely compact lithium-ion battery of the S 400 HYBRID with a capacity of 0.9 kWh in fit easily in its engine compartment, the lithium-ion battery of the Vision S 500 Plug-in HYBRID, at 10 kWh considerably stronger, requires more space. The accumulator is therefore located in the boot behind the rear seats and above the rear axle. This installation location offers decisive benefits: the weight distribution in the vehicle is balanced and the petrol tank retains a volume compatible with an extended range. In addition the position offers the best possible protection in the event of a collision.

In consonance with the modular design concept, the drivetrain of the Vision S 500 Plug-in HYBRID was in principle designed exactly like that of the S 400 HYBRID. A feature specific to the system was the additional clutch integrated between the internal combustion engine and the electric motor. It decoupled the two assemblies when driving under electric power alone, so that the highest efficiency was guaranteed in electric mode. As it was possible to fully integrate it into the torque converter housing, the separating clutch did not need any additional installation space.

A further important difference from conventional hybrid vehicles was its plug-in battery, which could be recharged at charging stations. This enabled the Vision S 500 Plug-in HYBRID to be driven up to 30 kilometres under electric power alone. The rapid-charge mode with a charging capacity of 20 kW took less than 60 minutes. A standard recharge of a totally discharged battery at a conventional wall socket, 3.3 kW took around four and a half hours.

The high-performance battery and the around 44 kW (60 hp) hybrid module enabled electricity-powered trips of up to 30 km, sufficient for most drives into town. And the Vision S 500 Plug-in HYBRID offered swift, very comfortable and locally emission free driving in this mode. At speed or on very steep climbs, the internal combustion engine kicked in automatically. Before closing the clutch, the vehicle electronics synchronised the rev speeds of internal combustion engine and hybrid module, so that switching-in proceeded absolutely jolt-free and unnoticeably.