General Motors expects to put electric hybrid cars into production by 2010 after unveiling its Flextreme concept at Frankfurt Motor Show which features E-Flex electric propulsion.

Bob Lutz, General Motors vice president of global product development, says that by 2012-2015, there will be “millions” of GM cars using the hybrid technology on global roads. Some will be diesel-electric, particularly those sold in Europe, while others will be petrol-electric which GM is developing for its home American market and Asia where diesel is less popular.

It intends to bring 12 models to market using the petrol-electric technology – called Two Mode – which has been developed with BMW and DaimlerChrysler.

The diesel-electric unit has a 55km range on battery only and emits just 40g/km CO2 on normal use with a 1.3-litre CDTi engine. The battery can be charged in around three hours through a standard 220 volt mains supply.

Flextreme differs from other hybrids in that it is always electrically operated. The diesel engine is there to increase range by charging the battery when needed.

Although the motor can be inserted into any GM model – and will be launched in the UK next year in the Corsa - the company chose to first display it in a concept MPV – one that shows strong hints as to the design of the next-generation Zafira, due in 2009-2010.

Key design traits expected to make it to production include reverse opening rear doors (FlexDoors) and gull wing doors (FlexLoad) giving access to the boot from the side of the car. Both were praised by customer focus groups. It also offers additional mobility by storing a Segway travel system beneath the boot.

GM is also developing an EcoFlex range of petrol engines, similar to Volkswagen’s Bluemotion range, as it pushes its environmental credentials.