The STS utilized the Sigma architecture, which was specifically developed to compete with European performance sedans. This RWD-native platform featured a near 50/50 weight distribution and a sophisticated four-wheel independent suspension with a multi-link rear configuration.
A major mid-cycle update in 2008 replaced the base 3.6L V6 with a Direct Injection (DI) version. This increased output from 255 hp to 302 hp, nearly matching the performance of the Northstar V8 while utilizing a more modern 6-speed automatic transmission
