GM has taken electric cars a step further at the 2009 Detroit auto show with the unveiling of the Cadillac Converj concept, a coupé loaded with interactive technology.

The four-passenger Converj uses GM's Voltec hybrid technology to provide up to 65km of emissions-free electric driving with an extended-range capability of hundreds of kilometres.

GM vice-chairman of product development Bob Lutz said the Converj concept had "production substance": "It's a logical extension of our plan to reinvent the automobile. It shows what a hybrid Cadillac could look like, with strong design and hybrid propulsion and a range of hundreds of kilometres.

The Converj Voltec system uses a 16kW/h, T-shaped battery, an electric motor and a four-cylinder internal-combustion generator - but the car is always driven by electricity.

The electric motor produces a claimed 120kW and 370Nm from zero revs for impressive acceleration and a top speed of 160km/h.

The battery pack has more than 220 lithium-ion cells that provide enough power to drive the Converj for 65km without using fuel or producing emissions. It can be recharged in less than three hours when connected to a 240V plug or about eight hours from a 120V outlet.

When the battery's energy is low the flex-fuel engine generates electricity to power the car, giving the Converj a much longer range than pure battery cars and the ability to refuel at a conventional garage if necessary. Electric energy is also stored during braking.

Styling is focused on a sweeping body line with 21" front and 22" rear rims, pushed to the edges of the body, and the Converj is finished with dark silver, three-layer paint. The glass roof has solar panels.

A smother belly, the smallest possible air intakes, low-profile rear-view cameras instead of mirrors and aerodynamic wheels that push air outwards for smoother body side airflow help to reduce drag.

The Converj has vertical and tail-light elements the use optic fibres.

Cadillac design director Clay Dean said: "Vertical lights are a Cadillac signature and the Converj builds on the brand's 'light pipe' technology with light emitting diode and high-intensity discharge elements front and rear."

LED INSTRUMENTS

The interior is trimmed in white synthetic suede - including the fascia - and black leather with polished aluminium and wood accents. Renewable materials are used throughout such as wool-blend carpeting, a silk headliner and suede made from recycled material.

The reconfigurable instrument panel has LED displays - including graphics for regenerative braking, battery charge level and power output - and touch-screen control for satnav, aircon and audio.

Check out our Detroit '09 special feature.