Sources say the 2010 Jaguar XJ (known in-house as X351) will use a modified version of the mostly aluminum architecture that made headlines for the XJ's 2004-model redesign. Wheelbase should stay at 119.4 inches, but overall length may be trimmed a bit, while width and height should go up somewhat. These changes would also apply to a long-wheelbase version, though we don't know yet whether that will continue. The restructured platform will be totally repaneled in a style much like that of the new XF . If anything, some sources believe the big sedan will be more radical, with high sides, a sloping low-profile 'four-door coupe' roofline, and hulking wheels tightly enclosed by muscular fender bulges. Also predicted are XF-style visuals like a big square mesh-filled grille, round headlamps in amoeboid housings, and a stubby high-set tail. The result, judging by one computer-generated image we've seen, could be a cross between theMercedes-Benz CLS and Chrysler 300.