The S-Type has been sold with V6 engines ranging in size from 2.5L to 3.0L, along with 4.0L and 4.2L V8 engines.
The supercharged S-Type R was introduced in 2003. It gets a supercharged V8 engine making 390 horsepower and can do 0 - 60 in 5.3 seconds. This version cost nearly $60,000 in the United States, which was only slightly less than a Dodge Viper at the time.
The S-Type is a rear wheel drive vehicle with a 5 speed manual transmission and a 6 speed J-Gate dual selection transmission.
In some markets, the S-Type is sold with a diesel engine. Due to the United States concerns with emissions and lack of concern for fuel economy (because those in power make big money from big oil companies), this diesel model was never imported here.
You can find plenty of these on the used car market if you know where to look. They tend to be too luxury for the basic local classifieds. Try looking online at Craigslist or eBay, or even a classic car classified site like Hemmings.