There are three engine options in the Jaguar S-Type lineup: one six-cylinder and two different V-8s. All S-Type Jaguars come equipped with a six-speed automatic transmission. For truly eye-opening power, the R model with its supercharged engine was the best, TheCarConnection.com found.
A version of the durable Ford Duratec 3.0-liter V-6 that powered the Ford Taurus 10 years ago can be found in the base Jaguar; 2008 versions massaged by Jaguar's engineers produce 235 horsepower and 216 pound-feet of torque. Although the S-Type's is more powerful than the Taurus version, Edmunds refers to it as a "low-quality Ford V6" that is perhaps unworthy of being in a high-end model like the 2008 Jaguar. They much prefer the 4.2-liter engine in both its naturally aspirated and supercharged versions, commenting favorably on the strong acceleration from both V-8s.
The Jaguar S-Type 4.2 has a naturally aspirated (neither supercharged nor turbocharged) 4.2-liter V-8 engine that produces a smooth 300 hp and 310 pound-feet of torque. This engine was the favorite of Kelley Blue Book: "We drove the S-Type 4.2 V8 and found it a pleasant experience. The car accelerates at a brisk pace with almost no vibration." They find the driving characteristics of the engine well suited to the overall package, and while the R makes more power, the combination of luxury and performance in the 4.2 is a nice compromise.
Speed demons will be drawn to the Jaguar S-Type R, which Car and Driver defines as "Powerful in R guise." One stab of the throttle dumps 400 hp and 413 pound-feet of torque to the tarmac, rushing this classy four-door to 60 mph in a scant 5.3 seconds. The R's standard supercharger and variable valve timing adds another 100 horsepower and 113 pound-feet of torque to the 4.2-liter V-8 found in the Jaguar S-Type 4.2, resulting in a sportier feel more akin to the performance of a Mercedes E63 or a BMW M5. While the R isn't quite as fast as these German sedans, it is also thousands of dollars cheaper.
For 2008, Jaguar has made the same six-speed automatic transmission previously slated for the R model standard for all S-Types. Kelley Blue Book reports that the "3.0 and 4.2 models receive the S-Type R's ZF six-speed automatic transmission." This transmission responds to driver inputs very well, and Kelley Blue Book further characterizes it as "One of the best in the industry...shifting happens in smooth, effortless order, with no lunges or jerks." Car and Driver follows suit, regarding it as a "Crisp-shifting six-speed automatic."
With gas prices constantly on the rise, fuel economy is becoming something even luxury car buyers need to take into consideration. ConsumerGuide rates the fuel efficiency of the 3.0 and 4.2 models of the Jaguar S-Type above the class average. Another nice feature: These two engines are clean burning. MyRide.com states that the "V6 and the atmospheric V8 achieved ULEV emissions status." The EPA rating for the 3.0 is 17 mpg city and 26 mpg highway, and the 4.2 gets 16 mpg city and 24 mpg highway.
High-performance engines like the S-Type R's naturally need more fuel, and although ConsumerGuide found this 2008 Jaguar model to be worse than average, it still returns a respectable 15 mpg city and 22 mpg highway. For a performance car with 400 hp, this is notable. Kelley Blue Book reports, "The S-Type R's engine is powerful enough to accelerate it from zero to 60 miles per hour in just 5.3 seconds, yet efficient enough to escape the government's Gas-Guzzler fuel tax."
The 2008 Jaguar S-Type has a plush ride quality that Edmunds says "follows Jaguar tradition by emphasizing easy steering and an overall relaxed driving experience over serious sporting pretensions." Kelley Blue Book supports that characterization, describing the S-Type's emphasis as "smooth, solid comfort rather than sporting performance." Even the sportier R is not very tightly sprung. Most reviewers find the combination of the controlled but smooth ride and competent brakes favorable for this type of sedan. ConsumerGuide's simulated panic stop tests of the S-Type result in "short and stable" stops, and Kelley Blue Book describes the suspension as "soft enough to feel luxurious, but still lets through an adequate level of road feel." Car and Driver was less impressed with the ride, stating, "The S-Type is really showing its age in...driving dynamics."