Sigma is General Motors' new full-size rear wheel drive automobile platform. The architecture debuted in 2002 with the 2003 Cadillac CTS and is adaptable for all wheel drive and extended wheelbase versions. Development of the Sigma platform began at Holden in Australia before 1998 as GWRD or Global World Rear Drive.

The long-wheelbase Cadillac STS replaced the front wheel drive GM K platform Cadillac Seville. The CTS was a replacement for the rear wheel drive Cadillac Catera.

Vehicles

Current vehicles based on this platform:

• 2003 Cadillac CTS
• 2004 Cadillac SRX
• 2005 Cadillac STS

Future vehicles using this platform:

Cancelled Sigma vehicles:

• Saab 9-7 - Saab will instead get a 9-7X based on the Chevrolet TrailBlazer
• Buick LaCrosse - The Sigma LaCrosse idea was replaced with a renamed FWD Buick Regal.

Sigma Lite

A so-called "Sigma Lite" variant might reach production in 2007 as a replacement for the cancelled Zeta platform. These vehicles would be built with less-expensive components and would be sold by Buick and Pontiac.

See also