The 2008 Cadillac STS comes in three flavors for the 2008 model year, and its V-6 offering is nearly as good as the substantially more expensive V-8.
The new base engine in the STS 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. (The 469-hp STS-V is covered in a separate review by TheCarConnection.com.)
The base 2008 Cadillac STS V-6 model is now virtually as fast as the V-8 model, and it saves fuel, with much better ratings of 17 mpg city, 26 mpg highway (versus 13/19 mpg for the V-8). Automotive.com points out that the STS Cadillac's 3.6-liter V-6 puts out 302 horsepower and 272 pound-feet of torque at 5,200 rpm. Meanwhile, the GM direct-injection fuel delivery technology makes this powerful engine remarkably economical. Car and Driver indicates that 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.” Edmunds confirms "the STS V6 is basically as quick as the unchanged STS V8." Kelley Blue Book also agrees, asking why anyone should pay extra for the V-8 engine. ConsumerGuide reports that the V-6 engine "provides strong acceleration...and has outstanding passing power."
According to Cars.com, all "engines use a six-speed automatic transmission" that Edmunds says is "slow to downshift." Cars.com notes that the transmission 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." Both the V-6 and V-8 models can be specified with rear- or all-wheel drive.
Kelley Blue Book finds that Cadillac STS "fuel economy proved surprisingly good, especially on long highway trips." EPA estimates are 17/26 mpg (3.6-liter V-6), 15/24 mpg and 14/21 mpg (Northstar 4.4-liter V-8, rear- and all-wheel drive).
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. ForbesAutos 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."
A new performance handling package is now offered on all models aside from the all-wheel-drive V-6 editions of the 2008 Cadillac STS and includes 18-inch chromed wheels, Michelin summer tires, and the larger Brembo four-piston brakes. ConsumerGuide finds that "reassuring brakes provide short, straight simulated panic stops" and adds that the 2008 Cadillac STS base suspension is great; however, the performance handling package option "triggers mild jitter on coarse or rippled surfaces." If the buyer opts for the optional Magnetic Ride suspension, the Cadillac STS will offer two options: Touring mode, which provides a "cushy ride and composed handling," and performance Sports mode, which is described as being "a little sharper and a bit stiffer." Edmunds actually finds the car handles just fine in Touring mode.