Almost all reviewers who drive the 2009 Cadillac STS emerge fans of its performance. Perhaps best of all is the realization that the STS’s V-6 engine performs nearly as well as the V-8, which costs a good deal more.
The new base engine in the STS is a 3.6-liter, 302-horsepower direct-injection V-6 teamed with a six-speed automatic. A 4.6-liter, 320-hp V-8 with a six-speed automatic transmission is also offered, and drivers can access a V-8 for a premium. (The 469-hp STS-V is covered in a separate review by TheCarConnection.com.)
The base 2009 Cadillac STS V-6 model is now virtually as fast as the V-8 model, and it’s much easier on fuel, with ratings of 17 mpg city, 26 mpg highway, versus 13/19 mpg for the V-8. Car and Driver confirms the figures: The available 4.6-liter V-8 offers only 18 hp more, costs an extra $9,000, and gets much lower fuel economy—"it's hardly worth it," they conclude. Kelley Blue Book also agrees, asking why anyone should pay extra for the V-8 engine. Edmunds confirms "the STS V-6 is basically as quick as the unchanged STS V-8," while Consumer Guide reports that the V-6 engine "provides strong acceleration...and has outstanding passing power."
In real-world driving, Kelley Blue Book finds that the V-6 Cadillac STS "fuel economy proved surprisingly good, especially on long highway trips."
Both the V-6 and V-8 models of the SRS can be specified with rear- or all-wheel drive. Both use a six-speed automatic transmission that Edmunds observes is "slow to downshift." Cars.com notes that the transmission of the 2009 Cadillac STS offers a "manual-shift mode, but like most it takes a moment or two to induce a shift," and if "the computer thinks the car needs a downshift, it's quick to override any actions to the contrary."
Forbes Autos reports "all versions deliver a fairly smooth ride with reasonably sporty handling." Kelley Blue Book says that the "STS tracked brilliantly in tight turns, though the steering response was somewhat soft and slow to react." The STS is known for good, sharp handling. Both models have a rather firm ride, but thanks to the standard Magnetic Ride Control, which can make almost instantaneous adjustments to damper firmness, ride comfort is quite smooth.
The optional Magnetic Ride suspension is a popular choice in the 2009 Cadillac STS. This feature has two options: Touring mode to provide a "cushy ride and composed handling," and performance Sports mode, described as being "a little sharper and a bit stiffer," says Edmunds, which reports that the car handles just fine in Touring mode.
ConsumerGuide finds that "reassuring brakes provide short, straight simulated panic stops" and adds that the 2009 Cadillac STS base suspension is great; however, the performance-handling package option "triggers mild jitter on coarse or rippled surfaces." The package is offered on each model aside from the all-wheel-drive V-6 editions of the 2009 Cadillac STS and includes 18-inch chromed wheels, Michelin summer tires, and the larger Brembo four-piston brakes.