That situation looks set to change this fall when the XF will get the 2.2-liter inline-four diesel from the Land Rover Freelander. Jaguar is currently modifying the engine, which was designed for transverse mounting in the Freelander, to be longitudinally mounted in the XF. The diesel is expected to be mated with an automatic transmission with automatic start-stop. This configuration should get the XF's CO2 emissions under 150 g/km (like the new Lotus Elise!). Unfortunately, we are unlikely to see this model in the U.S. market.
[Source: Top Gear]