The Saab 9-3 uses the so-called Epsilon platform. This is the platform for midsize front-wheel drive cars from General Motors. The Opel Vectra (2002) and the Saab 9-3 (2003 are the first cars equipped with. Since 2005, the epsilon platform is one of the most popular platforms from GM
The Epsilon platform is a relatively rigid platform with a torsional stiffness of 20,000 Nm / degree. The chassis has a standard MacPherson front and a multilink rear.
Saab stressed that from the beginning it took part in the development of this platform and it can be stated that the platform under the Saab 9-3 is not a one on one copy of the platform of the Vectra. The 9-3 is slightly longer, narrower and has a 25mm shorter wheelbase than the Vectra. The rear suspension of the 9-3 SS is somewhat reactive. Moreover, the modified suspension is stiffer horizontally and softer vertically so that both highway behavior as cornering is better than the original platform.
 
Cars with Epsilon platform:
* 2002 Opel Vectra
* 2003 Saab 9-3
* 2004 Chevrolet Malibu
* 2006 Cadillac BLS
 
Cars with extended Epsilon platform
* 2003 Opel Signum
* 2004 Chevrolet Malibu Maxx
* 2005 Pontiac G6
* 2005 Fiat Croma
* 2007 Saturn Aura
* 2008 Chevrolet Malibu
 
Cars where the Epsilon platform would be used  but was cancelled before production:
* 2006 Alfa Romeo Spider (replacement)
* 2006 Buick small