A performance-oriented V edition of the STS goes on sale as a 2006 model. Equipped with a supercharged 4.4-liter V-8 that produces 469 hp at 6,400 rpm and 439 pounds-feet of torque at 3,800 rpm, the STS-V can accelerate from zero to 60 mph in less than 5 seconds. The supercharged Northstar engine teams with a new six-speed-automatic transmission. Cadillac claims that during shifts, power is instantly lowered and then carefully ramped back up, making gear changes virtually unnoticed.

Special STS-V design touches include a larger, polished stainless-steel wire-mesh grille; a lower front fascia that contains a bigger grille; brake-cooling ducts; and a splitter to counteract lift. Rocker panels are lower than usual, and the special sculpted hood allows space for the engine's supercharger. The STS-V features 10-spoke, painted, aluminum-alloy wheels. Features inside include hand-wrapped leather surfaces, Oliver Ash Burl wood appointments and suede fabric seat inserts.