Introduced as a successor to the E-Type and powered by a 242hp V12 engine, the Jaguar XJS debuted in 1975 when gas-guzzling engines were not terribly popular. In just 5 years, Jaguar introduced a high-efficiency engine with different heads, higher compression ratio, and new electronic ignition. This brought the fuel economy up by almost 50%, and improved its marketability. Jaguar XJS parts remain difficult to find, as there weren't many of these cars built over the 20 years it was produced. Still, it holds a special place in the heart of many enthusiasts that want to get a piece of Jaguar history.