FLEXIBILITY is the word for the future of motoring - and in General Motors' case, the word's out.

General Motors (GM) - parent company of Vauxhall, Saab, and Chevrolet among others - has just showcased a vision of things to come in the company's Flextreme concept car.

It is a futuristic people carrier, or MPV, and the concept reveals the very latest development of GM's E-Flex architecture, which first previewed on the Chevrolet Volt Concept at the Detroit, USA, Auto Show last January.

Innovations include new loading systems including patented Flexload and Flexdoors, mixed with the latest advanced materials inside the cabin.

The eye-catching monocab body is designed with the environment in mind, and lightweight polycarbon panels, good aerodynamics, and lighter alloy wheels add further potential to the car's on-road capabilities.

The Flextreme uses the same electric hybrid drive system seen on the Chevy Volt, but in this case is coupled to a 1.3-litre turbo diesel engine, rather than the petrol power unit employed by the Volt.

Using an electric motor powered by a lithium-ion battery, the GM concept is capable of travelling up to 55km on electric power alone, a range that is seen as well within the needs of most European daily commuters.

This means they can travel to work and back without using any diesel, or creating any CO2 emissions.

The 1.3-litre diesel engine is based on the award-winning turbo unit found in Corsa and Astra, and does not drive the wheels through a direct connection. Instead, this engine recharges the batteries when they are empty, useful if no plug-in facility is available for the electric unit.

The Flextreme is also a clear reflection of Vauxhall's latest design language, with narrow boomerang-shaped lights and a sloping side shoulder line.

The concept's luggage compartment allows access through a pair of butterfly-style tailgate doors, which swing open upwards, making the tailgate accessible not just from the rear, but also from the side of the vehicle - useful when parking space is tight.

Flextreme's front doors open in the conventional fashion, but the back ones are hinged at the rear, removing the need for a central B-Pillar and providing excellent access into both front and back seats.

The seats, by the way, are anchored to the floor in single rails in order to free up extra foot space, while cameras mounted in the car's bodywork present the driver with an all-round view of Flextreme's surroundings.

The concept is on display at the Frankfurt Motor Show, in Germany, where SEAT delivered something of a surprise with the unveiling of its new Tribu concept off-roader.

A compact 4x4, the Tribu is the first model designed by design director Luc Donckerwolke since his arrival at the Spanish brand from Lamborghini.

This three-door sports utility vehicle showcases new design themes for SEAT, with more pronounced lines than previously seen in the firm's Leon and Altea ranges.

It is also highly significant in that this concept heralds the advent of a new wave of SEAT models.

Finally, Toyota stepped into the small car concepts breach at Frankfurt with its iQ, an ultra-compact, but space efficient, city car design exercise.

The iQ's flexible three-plus-one interior can seat three adults plus an additional child, yet lays claim to being the world's smallest four-seat passenger concept car.

A panoramic glass sunroof gives the interior an airy feel, while space-saving design and miniaturised technology help free up interior space - for example an ultra-compact heating unit that takes up less room in the centre console.

Toyota has not released details of the iQ's power source, saying only: "Factors such as size, and CO2 emissions cannot be ignored."

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