Bentley, the venerable British carmaker known for comfort and style, is moving into the fast lane of ultra-luxury cars with a new version of its flagship saloon, aiming to grab a bigger slice of a market tipped to double in size by 2018.

The 95-year-old brand, whose customers include Queen Elizabeth II and the Sultan of Brunei, is using this month's Paris auto show to launch the Mulsanne Speed under the strapline "the world's fastest ultra-luxury driving experience."

At 324,000 euros ($411,000), the model is not only Bentley's most expensive ever, but the eight-cylinder engine with a new combustion system will allow it to reach 100 kilometers per hour in 4.9 seconds and deliver a top speed of 305 kph (190 mph).

The launch is part of a diversification that will also see the Volkswagen-owned business branch into luxury sport-utility vehicles (SUVs) in 2016.

Such expansion is nothing new. Indeed, Bentley chief executive Wolfgang Duerheimer may be trying to replicate the success he had as R&D chief at Volkswagen (VW) luxury stablemate Porsche, where he extended a range of two-seater sports cars to embrace SUVs and coupés.

But analysts say it is vital if Bentley is to secure a larger share of a rapidly-growing market.

Deliveries of cars priced at 120,000 euros or more may almost double to about 133,000 vehicles by 2018 from 70,000 last year as the ranks of the super wealthy in the United States and China keep growing, according to forecaster IHS Automotive.

"The super-rich don't care about brand loyalty," Frankfurt-based IHS analyst Henner Lehne said. "They buy whichever model is hot."

With a dark tint finish applied to exterior grilles and wing vents, Bentley believes the new 5.57-metre version of the Mulsanne -- named after the fastest stretch of the Le Mans race track in France -- will comfortably fit into that category.

"Bentley is on the move," Duerheimer told Reuters in an interview late on Thursday. "The emphasis on performance has something to do with the lifestyle of our customers, it's part of their superlative aspirations."

Though Bentley accounted for just 0.1 percent of VW's record 9.73 million vehicle sales last year, it gives the German parent an aura of technical prowess while carrying out key research tasks, especially on engine technology.

Bentley has set a target to boost sales by about half to 15,000 vehicles by 2018, as part of VW's goal to overtake Toyota as the world's biggest carmaker.

GRAND PLANS

Duerheimer, who returned to Bentley in June after a brief stint as R&D boss at VW's Audi division, oversaw Porsche's push into SUVs in 2002 with the Cayenne, now the brand's top-selling model accounting for about half its deliveries.

In 2011-2012 when he first took the reins, he developed the business case and technology blueprint for the Bentley SUV which will be the world's most expensive four-by-four costing more than 160,000 euros.

A former racing engineer at BMW's motorcycle division who still drives a BMW GS model and touts a 365 kph personal speed record set in a Bugatti Veyron, Duerheimer's affection for performance is blatant.

He previously steered the launch of various performance-focused models at Bentley such as the Continental Supersports convertible which set a new world ice speed record at 331 kph.

James Medcalf, head of the Bentley Drivers' Club representing 3,500 enthusiasts around the world and owner of half a dozen Bentleys, said luxury and comfort remained the brand's top goals but performance was increasingly important.

"If you add more steps at the top of the ladder, many people will want to go there," the 78-year-old told Reuters. "The Speed version will add excitement to the Mulsanne."

Once production of the SUV is fully underway by autumn 2015, Bentley will decide on a possible fifth model line, Duerheimer said. Options include a two-seater sporty vehicle, a model to plug the 100,000-euro gap between the Flying Spur and Mulsanne saloons and new variants of the Continental GT, he said.

The brand also plans to introduce hybrid petrol/electric engines to about 90 percent of its lineup by about 2020, and aims to build a new R&D center and expand its operations in and around its Crewe, England-based headquarters, where it lacks a test track and other technical facilities, Duerheimer said.

Upgrading Bentley may take a decade and will require funding not yet approved by parent VW, he added. The brand is already spending almost 1 billion euros on the SUV and other models.

"We have grand plans," Duerheimer said. "The Mulsanne Speed gives proof of that."