2008 Cadillac STS V-6

We are strong advocates of increasing power in all engines, but this is not an issue we take lightly. Engines cannot be merely stronger; we also prefer them to be smooth and considerate. In this, the STS delights, being noticeably more powerful—up 47 horsepower and 20 pound-feet on the powerplant it replaces—as well as higher revving (7000 rpm versus 6700), better sounding, and marginally more fuel efficient. All that on regular fuel, too.