Jaguar XJ LWB Super 8

The big new XJ is exactly what Jaguar needs if its all-aluminium flagship is to compete on equal terms with its German rivals. Performance is still spot-on, while refinement and cabin comfort are improved. Details of UK trim levels will be confirmed closer to the car's launch date - which is expected to be late autumn.

America is the land of supersizing. Whether it's fast food, Hummer SUVs or mega-mansions that sprawl across hillsides, it's not only acceptable to demand more for the dollar, it's expected.

And recently, this has been a problem for Jaguar. The Coventry firm's XJ was received well in the States, yet it lacked that special something to make it an irresistible limousine. However, all that is set to change with the arrival of the new long-wheelbase XJ8 - and Auto Express has driven it first.

Specifically designed for success on the other side of the Atlantic, the latest XJ resembles a mini-Maybach and is priced so competitively, it's hard to justify buying the standard version. But how will the new model fare when it arrives in the UK later this year? Heading the line-up will be the £71,970 Super V8. As well as a supercharged engine, the US version boasts 19-inch alloys and a handsome mesh grille framed by xenon headlights. Yet due to its hi-tech aluminium body, the car is only 24kg heavier than its regular-sized sibling.

What's more, at 1,713kg the 127mm longer XJ is much lighter than the Audi 4.2-litre A8L and BMW's 745Li. That advantage really pays off on long journeys, where the Super can stay on the pace without incurring the fuel penalties of its heavier rivals - it achieves a combined economy figure of 20mpg.

In terms of performance, the newcomer is close to the standard model, and the Super completes the 0-60mph sprint in exactly five seconds. On the move, the XJ's lightness of touch is a delight, in contrast to the hefty feel of the German competition.

The Super V8 is the most thrilling LWB variant. Squeeze the throttle and it overtakes other drivers with supreme ease. The steering and brakes feel equally sharp and, while the competition damps out bumps with military firmness, the XJ uses wheel travel and Computer Active Technology Suspension (CATS) to glide over them.

Inside, an additional 10mm of height provides class-leading rear headroom, while lavish equipment in all three US trims we sampled comes close to Maybach excess. There are power sockets, DVD players with LCD screens and folding desks in the top two versions. But true business-class seats are missing, and while the Jag is quite roomy in the back, fully reclined front chairs can collide with rear occupants' knees.

As well as air-suspension and CATS, all models get power-adjustable pedals and seats, walnut trim and side curtain airbags. The mid-spec VDP adds boxwood inlays, lambswool rugs, fold-down trays, an electric rear sunshade, plus heated seats and steering wheel.

There is also a 320W Alpine sound system, which is linked to a six-CD autochanger. The awesome flagship Super V8 gets Brembo brakes and front park assist in addition to its go-fast hardware.