This teaser image shows the latest incarnation of the Chevrolet Volt electric car. The Volt is powered by a battery which can be charged by a tiny on-board engine if necessary. Although the picture gives little away, it shows a significantly more aerodynamic car than the original concept vehicle. Work in GM’s wind tunnel in Michigan, USA, is reported to have reduced the Volt’s drag by 30%, making it around 7% more energy-efficient.

In addition, engineers have had to balance the need for aerodynamic efficiency against the requirement to achieve enough under-body airflow to cool the battery pack. Road testing of the Volt is set to begin in 2008, with a production version of the car likely by 2010. Latest figures suggest it can run for 40 miles on battery power alone, which would be sufficient to power two-thirds of commutes in the USA.