I was reading an old issue of SAE Automotive Engineering (July 2003) and came across an article entitled "Jaguar builds LPG racer", which describes the Palmer Jaguar JP1. Serious Wheels has a reprint of the original Ford 2003 press release, which describes the car in more detail than the SAE article.
According to the SAE article, "the Jaguar JP1 and the Jaguar X-Type share the same V63.0L engine, but the lightweight JP1 with slightly more power reaches 60 mph (97 km/h) in only 3.6 seconds."