Bentley's lovely old bus is still going strong

Right now, in my driveway, there sits a Bentley Continental Flying Spur. This is the new breed of Bentley, created with the engineering might of the Volkswagen group, using mechanical components derived from the fabulous but misunderstood VW Phaeton then developed, refined and honed to the limit.

Its engine is a twin-turbo W12, its aura is exactly what that of a modern Bentley should be (opulent, a legitimate collision of retro and hi-tech, a fine sporting luxury saloon of stupendous pace). The only thing wrong with it is that it thuds and jars over bumps in a way it really should not, regardless of which suspension setting, out of four, is in use.

The Continental family is the Bentley future. But I'm not going to tell you more about it here, because Bentley also makes an anachronism. Maybe it does this to keep the faith, to prove it has not forgotten its heritage, but it is nevertheless extraordinary that Bentley still makes a car seemingly as tall as a house, as imposing as a luxury liner and powered by an engine designed half a century ago. Extraordinary, and also strangely heart-warming: can the venerable Arnage really be justified in the modern business world?

It can. A little peek into the rarefied world of the über-Bentley buyer reveals why. There's a year-long waiting list for the Flying Spur. "I'll have one, now," says a typical customer. "But it's not for sale yet," says Bentley. "Then I'll take an Arnage to tide me over while I wait." This happens, and when the Spur is ready, the customer will likely as not keep the Arnage anyway.

The Arnage is the last pre- VW-era Bentley, the last model family to have also been available before the great split between Rolls-Royce and Bentley and each marque's adoption by rival German companies (Rolls-Royce, of course, went to BMW). The Rolls version, now gone, was called the Silver Seraph, but since the landscape was redrawn the Bentley has undergone two major under-the-skin revamps. The second is the reason for this report, and it has led to some intriguing numerical facts.

The top Arnage is called the Arnage T, the current incarnation of the tyre-smoking battle cruiser whose incongruous genre began with the mid-1980s Bentley Mulsanne Turbo. The Rolls/Bentley V8 was launched as a 6.23-litre unit in 1959, a lightweight, all-aluminium engine designed to replace the previous straight-six. It had to be much more powerful than its predecessor but take up no more space and fit behind the same radiator. These constraints led to design features which, unbeknown to original designer Jack Phillips, were to prove very useful in today's world.

These features are compact, wedge-shaped combustion chambers, which allow narrow cylinder heads, and very short exhaust ports so a minimum of heat escapes into the cooling water, thus easing the load on that restricted-size radiator. Today, the wedge chamber is known to be very good for exhaust emissions, and the short ports keep the exhaust gases hot - which gets the catalytic converter working more quickly after a cold start.

And those numerical facts? Today's engine , which has grown to 6.75 litres, is 2.5 times more powerful than that 1959 original, uses 60 per cent as much fuel and emits 99 per cent less toxic gas. It delivers a healthy 500bhp, but more significant is its torque, or pulling ability. Turning metric for a moment, the figure is 1,000Nm, obviously an attractive target for the Bentley engineers; it translates to 738lb ft in British parlance. It's still a low-revving engine, though, its best efforts waning after 4,200rpm. It's the closest in power delivery to a steam engine that you'll find in a car today.

To reach these latest outputs, the V8 has received a new pair of lower-inertia turbochargers. More significantly, its old-fashioned valve-gear, with a single, central camshaft and long pushrods, has gained roller rockers which reduce friction and allow much closer control of valve timing. And to make the most of the extra energy, the Arnage has gained a modern ZF six-speed automatic transmission in place of the old GM four-speeder.

It locks the engine positively to the driving wheels much of the time, so the squashy, elastic-band feel of old is largely banished. You're now more likely to use the manual override mode, except that with such epic pulling power you soon realise the pointlessness of manual intervention.

So you just let the engine woofle away with its menacing burble, and revel in the way the new transmission lets you control the rate of motion - 0-60mph in just 5.2 seconds, if you have an oil well to spare - so much more accurately. But you still need to be careful with that right foot, because the step-off can be savage if you're not. The top speed is 179mph, incidentally, an extraordinary pace for a car with such a bluff nose.

With the engine's new obedience comes a more subtle ESP system to let you exploit your new precision of control. Previously, if the ESP detected the beginnings of a tail-slide, and the vast ill-directed momentum this could entail, it shut down all turbo boost instantly. This did not make for fluid progress.

Now, power is carefully modulated and you can have much more fun, to the extent that the vast Arnage feels surprisingly wieldy when you're pressing on. Switch off the ESP and lurid, smoky slides are the undecorous result: amusing for the driver, alarming for any onlookers and expensive on tyres.

Even at a heady £175,000, though, the Arnage T is far from perfect. The wipers judder, there's no flick-wipe and the steering column isn't adjustable for reach. At an average 14.5mpg the fuel thirst is close to irresponsible.

It rides over bumps better than the Flying Spur (so it should with over two-and-a-half tons to squash the tyres) but otherwise the newer model is a far more complete and capable car.

However, like the Routemaster bus, which has a similar front grille, the Arnage is a splendid anachronism. Most owners will have another car anyway (usually a Mercedes, apparently), so who's going to be complaining?

Heavy price, heavy car

Despite its £175,000 price tag, the Arnage T isn't perfect - the windscreen wipers judder and the steering column needs to be more adjustable - but it's great at riding the bumps, not surprisingly, as it has two-and-a-half tons holding the tyres down.