Stuttgart  - Mercedes showcased at the Frankfurt Motor Show (IAA) what it calls the "first three-litre car" in the premium luxury class, the Vision S 500 Plug-in Hybrid with a range of up to 30 kilometres on clean electric drive.

Combined with the electric drive Mercedes lists consumption of the "experimental vehicle" at only 3.2 litres per 100 kilometres with a carbon dioxide emission figure of 74 grammes per kilometre.

The drive system consists of three main components - a powerful V6 petrol engine with a next-generation direct injection system, a 44 kW/60 hp hybrid module and a lithium-ion battery with more than 10 kWh of storage capacity that can be recharged at charging stations.

The Vision S 500 Plug-in HYBRID accelerates from 0 to 100 km/h in 5.5 seconds. Mercedes CEO Dr Dieter Zetsche said the car was a "milestone on our path to zero-emission mobility," but board member Dr Thomas Weber conceded that it would be sometime yet before the car could go into serial production.

"We've already got all the key technology we need for such a dream car, which is why I see it being included in the next generation of the S Class. The important thing now is that our development work be accompanied by the establishment of a full-coverage infrastructure that will allow the potential of this innovative drive system to be fully exploited," Weber said.

The high-performance battery and the 44 kW/60 hp hybrid module enables the vehicle to drive up to 30 kilometres on electric drive, sufficient for most city trips. The petrol engine automatically adds its power to that of the electric motor when travelling at high speeds or driving up steep inclines. Before closing the clutch in such cases, the vehicle electronics synchronises the engine speed with the hybrid module's rotational speed so that the engine is activated without the driver noticing. (dpa)