For 2008, STS will be the first GM vehicle equipped with a new 3.6-liter direct-injected V-6 engine. The new base powerplant, with 298 horsepower (222 kW), delivers 40 more horsepower; and torque is increased to 268 lb.-ft. (371 Nm) - up from 252 lb.-ft. (348 Nm) on the current base engine.

The new direct-injected 3.6L will be mated to the Hydra-Matic 6L50 six-speed automatic transmission, the first pairing of this transmission with a V-6 engine. Additionally, the STS V-6 will continue to be available with all-wheel drive (AWD) for 2008.

Advantages of the new direct-injected engine include a 25-percent reduction in cold-start hydrocarbon emissions. Additionally, despite the 15-percent increase in power, fuel economy is expected to increase slightly.