Fisker will display the aluminium space frame underpinning its upcoming Karma premium plug-in hybrid electric vehicle at the Geneva show next month. It claims the frame “incorporates new levels of rigidity and strength that will give the [car] first world-class ride and handling characteristics”.

The space frame will house the ‘Q-Drive’ series-hybrid powertrain which consists of a two-litre turbocharged GM Ecotec engine/generator set, A123 Systems lithium-ion battery and a rear-mounted 403hp traction motor assembly.

Fisker said engineers achieved the best balance between weight and size by using 5,000- and 6,000-series aluminium alloys and a unique extrusion-intensive architecture.

“Our top priorities when we designed the Karma’s aluminium space frame were that it have extremely high torsional rigidity and could be easily modified to accept Karma model variants,” said CEO Henrik Fisker. “We benchmarked some of the world’s best cars to create an all-new space frame that will deliver an exhilarating experience behind the wheel.

A super-structural tunnel running down the car’s centerline acts as the car’s backbone. It houses the battery pack and acts as a torque tube connecting front and rear sections. For optimal strength the space frame is joined with 79m of precision welding and 1,058 self-piercing rivets. Each technique is used independently only where necessary to ensure top quality and durability.

Fisker claimed few cars would match its statistics: static torsional rigidity of over 33,000 Nm per degree and static bending rigidity over 23,000 N/mm. Dynamic stiffness was also claimed to be “world class”.

Front impact protection includes a patent-pending, multi-cell tempered aluminium crush box that displaces high-impact energy away from passengers. Its unique design allows it to be easily replaced, reducing repair costs that could lower insurance premiums. Dual Phase 600-Series steel reinforced components in the doors and Bpillars provide substantial side impact protection. The lithium-ion battery’s location in the centre of the car puts it farthest from impact areas, Fisker said.

Valmet Automotive will assemble the space frames in Uusikaupunki, Finland.

The initial four-door Karma model will be followed by two variants and a second line of lower cost, high volume ‘premium green’ cars by 2012.