If you thought the new Jaguar XF was a radical departure, hold on to your cap, because if reports coming in are to be believed, the replacement for the flagship XJ sedan could be even more revolutionary for the traditionally staid British luxury marque.

Granted, you can't tell much from these spy shots. They were snapped while a mechanical prototype was undergoing testing in the Arctic Circle, and it's clad in the bodywork of the current model. However, based on Jaguar designer Ian Callum's reported fascination with the svelte form of the Mercedes CLS, insiders suggest the next XJ will be wider and lower and take on the four-door coupe approach. Code-named X351, the next XJ will continue with its all aluminum construction and could be unveiled in the spring of 2011...that is, assuming Jaguar's new owners don't decide to go another way.

[Source: World Car Fans]