Back in the spring of 2008 when General Motors took us on a tour of its wind tunnel facility, chief engineer Frank Weber emphasized the importance of aerodynamics in maximizing the electric driving range of the Volt. At that time, all we got see was a one-third scale model covered in various colors of duct tape. However, GM's aerodynamicists, including Nina Tortosa, explained that even at lower speeds, resistance to air-flow played an even bigger part in efficiency than the car's mass.

In the latest in a series of videos on the Volt development program, Tortosa describes the evolution of the Volt's shape as it has made its way to production form. Rather than a model, she uses a smoke wand to show the air-flow over one of the pre-production IVER vehicles. From concept to production, the Volt picked up seven miles of electric driving range just from changing the shape of the body. The rear, where the air-flow separates from the body, is one of the most critical areas and has to be carefully shaped to avoid uncontrolled turbulence. The final Volt shape came in second only to the tear-drop shaped EV1 (cD 0.195) in drag coefficient but with a more conventional four door body.

[Source: General Motors]

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