The upcoming XJ limousine will be as much of a departure from today's staid old XJ as the mid-sized XF, which has become a global star for the brand, was from the unloved S-Type it replaced.
The new XJ will also dig deeper into the future styling direction set by Jaguar's chief designer, Ian Callum. And it could look more like a Mercedes CLS-style four-door coupe than a traditional upright British luxury car.
Jaguar insiders say the new XJ - codenamed X351 - will be much lower, with a sleeker look and a new nose which picks up the styling cues already used in the XF.
The new look is being keep a closely-guarded secret, which explains the heavy disguising on an XJ prototype just caught in cold weather testing.
But the mechanical package will not be any surprise, as Jaguar is saving money on the new XJ by using the existing aluminium chassis package of the existing car. It will also keep a revised version of Jaguar's current V8 engine as the original powerplant choice, the newer V8 developed by Land Rover, could not be fitted beneath the XJ's low-line bonnet.
A full re-work of the XJ is not likely until 2015, which means the basic package will have been running since 2004 - despite a minor facelift just over a year ago.
The X351 is not expected in the Jaguar lineup until the middle of next year, but the car should be seen for the first time at the Frankfurt Motor Show in October.
While the new XJ is out and running, there are growing rumours from Britain of a born-again E-Type sports car from Jaguar.
The project is a pet project for Jaguar's new Indian owner, Ratan Tata, who says the company needs a sports car hero.
The car is likely to be called the XE and will be similar in size and layout to the XF sedan.
But the XE is not coming any time soon with a first appearance not expected until the Geneva Motor Show in March of 2011.