GM Sigma platform

2010 Cadillac CTS Wagon

Sigma is General Motors' mid-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 V-body Cadillac Catera.

The Sigma platform has a four-wheel independent suspension with control arms in front and multi-link in the rear. GM's High Feature V6 and Northstar V8 are most common, though the small-block V8 has also been used. GM's 5-speed 5L40/5L50 automatic transmission is used throughout the range.

All Sigma vehicles are built at the purpose-built Lansing Grand River factory in Lansing, Michigan.

Vehicles based on this platform:

• Cadillac CTS 2003–2007
• Cadillac SRX 2004–2009
• Cadillac STS 2005–2011 (SLS continues in China)

Sigma II

Sigma II, larger and wider than its previous counterpart, debuted with the 2008 CTS, and shares more parts with the larger Zeta than the smaller Sigma I. Sigma II is more flexible and features the Direct Injection 3.6 HF V6 as its primary engine and a new more powerful 3.6 L DI HF V6, as well as supercharged smallblock V8 for the Cadillac CTS-V. Sigma will stay a Cadillac exclusive. Coupe and wagon versions arrived for the 2011 model year. Vehicles using this platform:

• Cadillac CTS 2008–present
• Cadillac CTS-V 2009–present