If the rumours are to be believed – and there’s enough 2010 Jaguar XJ rumours getting around – Jaguar will unveil its all-new XJ this coming July.

Known internally as Project X351, the new XJ is expected to borrow design cues from the current XF, utilising a sportier roof line and more aggressive styling all round.

While the new XJ was originally planned to be a re-skinned version of the existing XJ, a mid-project decision to go all-new means that Jaguar’s 2010 flagship will be the first to launch with a significantly re-tooled body and new engines.

While the styling is said to be inspired by the XF, the roof line will be taller to better accommodate the chauffeur-driven elite, and insiders say the XJ will be more eye-catching.

The range-topping XJR will carry the marque’s new 375kW (503hp) direct-injection 5.0 litre V8, which should ensure the car competes nicely with its competitors at Bentley.

Jaguar’s new 202kW (271hp) 3.0 litre diesel V6 will also be available, with fuel economy believed to be around 7.1 l/100km.

There’s no saying yet exactly how the new XJ will look, but with only a few months between now and the supposed unveilling date, we’ll know soon enough.

[via AutoCar.  Images Auto Express]