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GM: Aerodynamic design increases Volt’s range

Bob Boniface of GM showed this comparison of Volt designs during a Thursday presentation. Photo credit: JOE WILSSENS
TRAVERSE CITY, Mich. -- The design team for General Motorsí Volt plug-in hybrid car has added six to seven miles to the carís electricity-only range by improving the carís aerodynamics.

ďAir does not like to go around sharp corners. It creates turbulence and drag,Ē Bob Boniface, GMís director of design for the Chevrolet Volt and E-Flex studio, said on Thursday, Aug. 14, at the Management Briefing Seminars.

Boniface therefore made numerous changes to the original conceptís design. The changes were conceived in order to support the Voltís goal of having a 40 mile range purely from the carís electric charge. More than 70 percent of U.S. commutes are less than 40 miles, GM says.

Boniface explained a number of those changes.

The concept originally had a blunt front end with a sharp crease on the corner. The production version now has a very rounded look.

The production carís grill texture is largely sealed up. The design now sends the air down the side of the car and not through the engine compartment.

A curving crease down the back corner of the concept has been smoothed. Both there and on the spoiler, Boniface said, ďYou want an aerodynamic Ďtripí device so air leaves the car very quickly and cleanly.Ē For the spoiler, GM added a 5 millimeter Ďtripí device, he said.

Bob Boniface, GMís director of design for the Chevrolet Volt and E-Flex studio Photo credit: Joe Wilssens

Looking in the mirror

The conceptís sideview mirror started with a patch mount, where the structure holding the mirror sticks out horizontally from the door. For the production version, that was changed to a post mount. The mirror now sits on a post lifting from the vehicleís side.

The changes to the mirror and spoiler each cut drag by 5 counts, he said. ďWhy should you care, when you probably donít even know what a drag count is,Ē he added.

For every 10 drag-counts reduction by the aerodynamic design, the design team added 0.55 miles of highway range on the vehicleís electric charge. In total, the team cut the conceptís drag counts by 120, thereby adding six to seven miles to the carís range on the charge.

Those efforts are helping GM reach its target range of 40 miles on the electric charge for the Volt.

You can reach James B. Treece at autonews@crain.com

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