BERWICK-UPON-TWEED, U.K. – Some 1,500 years ago, the massive brick ramparts of Bamburgh Castle near here girded against Viking hordes from across the North Sea.

Its military role long retired, the outpost recently was a stopover for media drives of the Bentley Mulsanne, an all-new sedan for the auto maker tasked with defending against another invader – the Rolls-Royce Ghost.

However, suggesting the $285,000 Mulsanne competes against the $245,000 Ghost draws nothing but grumbles from the folks at Crewe. After all, these British rivals have had pistols perpetually drawn since Volkswagen AG and BMW AG broke up their dysfunctional relationship more than a decade ago.

“This is no Ghost,” Bentley Chairman and CEO Franz-Josef Paefgen quips along a drive of the Scottish borders and Northumbria. “It is the real thing.”

But bear this in mind: The Mulsanne plays at the very top of Bentley’s range, while the Ghost occupies the lowest rung on the Rolls-Royce ladder. Timing-to-market also roughly coincides, as do their engine displacements and, as usual, each auto maker will fashion option packages to meet buyers’ every desire.

So with its borders breached, Bentley brings the Mulsanne later this year to defend a cozy market segment the auto maker carved out for itself with the launch of the Continental range in 2003. The Mulsanne also effectively replaces the Arnage, which until now served as the auto maker’s principle V-8-powered land yacht.

The Mulsanne, however, warrants little comparison with its predecessor. The two cars weigh the same, but the Mulsanne is faster and more fuel-efficient, and its dimensions purr “drive me” like no other Big Bentley to come before.

That said, initial driving impressions recall a fat uncle who always took up too much of the couch during the holidays. Creeping through the gates of Bamburgh Castle, which mind you were built to accommodate cavalry, takes assistance from Bentley public- relations folks stationed on the other side.

Out on the maddeningly narrow rural roadways of the U.K, the Mulsanne’s girth is no picnic for the uninitiated, either. With each passing lorry, the left front tire of the right-hand-drive Mulsanne goes “thumpety-thump-thump” along the shoulder.

But turning onto the A1, or “The Great North Road” as locals call the double-lane highway, the Mulsanne starts working some old-school Bentley charm. Relax your shoulders into the buttery leather seat, ease into the throttle and watch the countryside blur past.

Calling the redesigned 6.75L pushrod V-8 responsive would be like calling the Mona Lisa pretty. With its 752 lb.-ft. (1,020 Nm) of torque available at just 1,750 rpm and twin turbochargers, the engine effortlessly propels the 5,700-lb. (2,585-kg) Mulsanne.

’11Bentley Mulsanne
Vehicle type Front-engine, rear-wheel-drive 4-door sedan
Engine 6.75L twin-turbo OHV V-8
Power (SAE net) 505 hp @ 4,200 rpm
Torque 752 lb.-ft. (1,020 Nm) @ 1,750 rpm
Compression ratio 10.8:1
Transmission 8-speed automatic w/paddle shift
Wheelbase 128.6 ins. (326.6 cm)
Overall length 219.5 ins. (557.5 cm)
Overall width 75.8 ins. (192.5 cm)
Overall height 59.9 ins. (152.1 cm)
Curb weight 5,700 lbs. (2,585 kg)
Base price $285,000
Fuel economy 16.7 mpg (14 L/100 km) combined EU cycle
Competition Rolls-Royce Ghost, Maserati Quattroporte
Pros Cons
Endless torque stream Likes its elbow room
Surprisingly nimble Dreadful fuel economy
$285K masterpiece $285K masterpiece

Variable-valve timing and an imperceptible cylinder-deactivation system improve efficiency on a nonetheless thirsty powertrain.

An 8-speed ZF transmission shifts quickly and smoothly. Steering wheel-mounted paddle shifters, a first for Bentley, satisfy drivers wanting a little more interaction. But the powertrain is smart enough to do the work itself, even under more spirited driving.

While this bruising sedan likes to take up an entire lane and weighs more than a Chevy Tahoe fullsize SUV, the Mulsanne remains surprisingly nimble. An all-new chassis unique to the Mulsanne is lighter, stiffer and more technologically advanced than any previous Bentley.

Four specially tuned motoring modes – Bentley, Sport, Comfort and a driver-configurable Custom setting – are accessed via a rotary dial near the gearshift selector to optimize suspension and steering.

Each mode works alongside the real-time air-assisted damping system, massive disc brakes with Bentley-branded calipers and 21-in., Z-rated tires that put a big confident patch of rubber on the roadway.

On a sprint through the Northumberland National Forest, where the roadway features tight switchbacks and sudden elevation changes, the Mulsanne handles admirably if not spectacularly, by bailing out drivers captivated by sprawling fields of Scottish heather.

Inside, the Mulsanne is quiet as a confessional. High winds off the sea prove no match for the air-tight cabin, and even the wiper blades glide softly across the windshield during a cloud burst.

Leather and wood dominate the interior, and Bentley’s hand-crafted work is plainly evident. It’s easy to imagine the employees at Crewe hand-stitching our tester’s linen and redwood leather or running a plane across its Vavona wood trim.

A wood waistrail, unique to the Mulsanne, encases the cabin. In the rear of the vehicle, it circles unbroken around its passengers to impart a bygone era of motoring through the English countryside.

At the same time, the Mulsanne embraces the latest technology. A handmade, leather- lined iPod drawer softly withdraws from the dash, unlocking a 14-speaker audio system of flawless sound quality, and an 8-in. multi-media screen hides behind an electronically operated veneered door.

Of particular note, the Mulsanne’s redundant navigation screen inside the driver- information center easily ranks as the industry’s most sophisticated.

Using a combination of arrows and timely voice commands, it’s nearly impossible to take the wrong exit in a roundabout, despite driving on the opposite side of the road from the opposite side of the car.

Old-world organ-stop pulls for opening and closing air vents serve as a pleasant contrast to such modern gadgets.

The exterior design is meant to recall the Bentley S-Type of the 1950s, the auto maker says. We say it resembles a modern heavyweight boxer – a square jaw with broad, chiseled shoulders flowing to a taut mid-section. Its stance conveys the power of a haymaker and the quickness of a left jab.

Bentley executives expect the Mulsanne to account for 10% of annual sales. With 2010 deliveries tracking at 5,250 units, we’re talking some 200 fewer cars than Ford Motor Co. might sell in a single day in the U.S.

And while the average Taurus customer probably lost most of his retirement during the recession, the average Mulsanne buyer still sits on more than $25 million of disposable assets.

So as niche-ified as the Mulsanne might appear, it still provides a valuable lesson: Don’t dally about when someone jumps into the ring.

Instead, deliver a knockout.