American carmaker Fisker Automotive is demonstrating the technology behind its Karma hybrid model for the first time at the Geneva Motor Show 2010. Fisker has developed an extremely rigid but nevertheless lightweight aluminium space frame for its hybrid luxury limousine with its electric drive. The Fisker Karma is the world’s first luxury car to use plug-in hybrid electric vehicle (PHEV) technology.

Fisker Automotive has developed the Karma space frame around the company’s Q-Drive series hybrid power train. The Q-Drive comprises a 2.0 litre turbocharged engine/generator unit, a lithium-ion battery and a 403-bhp (375 kW) rear-mounted drive unit. The space frame of the Karma has a high rigidity and uses 5000- and 6000-series alloys. “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,” explains Henrik Fisker, CEO, Fisker Automotive. It is planned to build the Fisker Karma as limousine, coupé and cabrio.

A super-structural tunnel running down the car’s centreline acts as the Karma’s backbone. It not only houses the battery pack but also acts as a torque tube connecting front and rear sections. To ensure optimal strength, the Karma’s space frame is joined using 79 metres of precision welds and 1,058 self-piercing rivets.

By 2012, the four-door version of the Karma will be followed by two variants and a second, more budget-priced line of eco-friendly luxury cars, for which high-volume production is planned. The price for the Fisker Karma in Germany is expected to be about 75,000 euros.