Jaguar XJ8 Sovereign LWB

With strong sales of Jaguar's XJ set to continue, now is the perfect time to launch a long-wheelbase flagship. The LWB is great to look at and impressively quick, but far from perfect ride quality will make German alternatives more appealing for some. However, let your heart rule your head and there are few better ways to travel than in this characterful Jag.

Hen nights and birthday parties have done nothing for the reputation of stretch limousines. Take a trip into any busy city centre and you're bound to see 25-foot Lincoln-based giants plying their trade between the pubs and clubs.

But those who travel in the back seats for business rather than pleasure have some far more desirable and understated transport to choose from - and Jaguar is hoping to catch their attention with this new long-wheelbase version of its luxury XJ saloon.

We took on the roles of chauffeur and chauffeured in the first right-hand-drive UK model to come out of the factory. So what does the newcomer have to offer? First impressions are that this is one enormous saloon. The rear doors have increased in length by 125mm, and there is a subtle seven-millimetre rise in roof height to give back seat passengers more headroom, too.

Less impressive is the boot, which retains the standard car's shallow luggage space. Thankfully, though, none of the grace of the XJ's lines has been lost - it's still a beautiful luxury saloon.

Climb into the rear, as most owners of this XJ8 Sovereign surely will, and you're greeted with real opulence. Along with the sumptuous leather trim, passengers have electrically operated sliding back seats with lumbar support.

Jaguar offers LWB customers a vast array of in-car entertainment, and the model we drove was equipped with a full DVD video system, controlled via a touch screen on the dashboard or a control panel in the armrest of the rear seat. With a button for every imaginable adjustment, the layout is a far cry from the single-control systems found in top-flight BMW and Audi models - but many buyers may prefer Jaguar's more conventional system.

When the chauffeur takes a day off, it won't be difficult for the owner to get comfortable behind the wheel. Despite its size, the XJ LWB doesn't feel unwieldy or difficult to drive, and the turning circle is only 34cm wider than that of the standard version.

Head out on to the highway, and it's only on twisty B-roads that the extra length makes the stretched Jag seem less nimble. Unfortunately, despite some changes to the suspension, there's little improvement in ride quality, so coarse motorway surfaces make themselves felt through the cabin.

The good news is that in adding no more than the weight of a suitcase - 24kg - the lengthened body has had no tangible effect on the performance, economy or emissions. As a result, the 300bhp, 4.2-litre V8 powerplant still launches the XJ from rest to 60mph in 6.3 seconds, accompanied by an aural treat from the engine bay.

With plenty of torque on offer right across the rev range, acceleration is effortless, and the six-speed automatic gearbox provides slick changes, even in sport mode. A supercharged V8 version of the LWB is also available, providing a massive 400bhp, but we are baffled as to why anyone would need the extra performance - particularly if owners are going to spend most of their time in the back!

Value for money isn't something normally associated with luxury cars, but Jaguar has made a definite effort to keep the extra cost of the stretched XJ to a minimum. At £1,750 more than the standard model, the extra centimetres are cheap compared to the Mercedes S-Class L, which is £2,720 more than the shorter model, and Audi's lengthened A8, which adds £3,370 to the bill.

For most UK buyers, the standard XJ is large enough, so it's no surprise that 80 per cent of the LWB versions are bound for the USA. However, if you want more character than other stretched luxury cars can offer, Jaguar's flagship will be a welcome alternative.