Bentley, British maker of ultraluxury cars, is tearing up the sales charts.

In 1993, Bentley sold 993 cars to its well-heeled customers. But by 2006, the company sold 9,386 automobiles, an increase approaching 1,000 percent -- a story not matched by any auto company anywhere, luxury or otherwise.

What's behind it? A big increase in the number of millionaires, for one thing. The number of people with more than $1 million in assets rose 8.3 percent to 9.5 million in 2006, according to Merrill Lynch and Cap Gemini's annual survey of world wealth. Collectively, these people own $37.2 trillion in assets.

A good share of Bentley's growth has resulted from growing affluence in such nations as China and India, which are seeing some of the highest growth in the number of millionaires.

With the growing trend of customization and personalization in the worldwide auto industry, it should come as no surprise that those with wealth would head for a company that can make a car expressly for them.

"What makes Bentley automobiles different from pretty much any car in the world is that we are truly the only hand-built autos still available," Bentley spokesman David Reuter said. "When you look at various ultraluxury car brands out there, all of them have a certain level of automation in their production process. It's fair to say that Bentley has some, too. But when they come to our factory in Crewe, England, and see their car being built, a light bulb goes on.

"We have a level of hand craftsmanship unparalleled by any other carmaker."

Another boost in sales came when the company was purchased by Volkswagen in 1998, Mr. Reuter said.

"It's made all the difference in the world. When they purchased Bentley they committed to modernizing the factory in Crewe. ... They also made a commitment to the brand's wish for its future product lineup -- namely the Continental series," Mr. Reuter said.

Strong aspirational headwinds also have helped increase sales success at Bentley. Building on a demand by people who always wanted a Bentley but couldn't afford one, the English manufacturer introduced several less expensive models, each of which greatly exceeded sales targets. They included the Continental GT Coupe in 2004, the Flying Spur sedan in 2005, and the Continental GTC Convertible in 2006.

But the Continental models still are Bentleys, with the luxury the company is known for -- and a price tag that still would shock the average consumer. The Continental model range starts at $170,990 and tops out at $199,990 for the new 2008 Continental GT Speed coupe. By way of comparison, the company's top drawer Arnage models start at $221,990 for the Arnage R sedan and top out at $263,990 for the Arnage RL sedan.

The company says it has no plans to build on the success of the Continentals by introducing a sport utility vehicle.

"You've heard some stories and speculations that Bentley would build an SUV. But we've been pretty vocal in saying we don't plan doing that," Mr. Reuter said. "An SUV wouldn't be a Bentley, and it would be very difficult to fit that into our line. SUVs don't go with our heritage either, and our cars come with a storied history. That's been very important to us."

Guarding a company's image while improving sales is a challenge for makers of any luxury item. If a product becomes too common, it can lose cachet and prestige.

"That's certainly a potential problem for Bentley," said Kelley Blue Book Editorial Director Jack Nerad. "Depending on your community, if you are driving a Mercedes S Class or a BMW Seven Series, those are perceived by others in the neighborhood as not being so elite because everybody on your block has one. That's not true on my block or perhaps yours, but there are plenty of blocks in the U.S. like that. People who drive these kinds of superluxury vehicles want to exhibit the fact that they are successful. One way to do that is to drive a car that is quite visible."

Managing a hot selling luxury brand is a tough act, albeit one that plenty of car companies would like to have.

Looking back over automotive history, some brands have failed miserably at managing to balance prestige and exclusivity with good sales volume.

Packard, once the United States' most prestigious brand, found sales success when it introduced a lower priced One Twenty to its lineup -- but it also diluted the brand's image. Down the road, the model, which had gone out of production, was blamed for the company's demise in the mid-1950s.

Cadillac's efforts to increase sales also resulted in failure with the LaSalle during the 1930s and earl 1940s, the Cimarron in the 1980s and the Catera in the 1990s. They finally found success with the CTS, a sophisticated, stylish entry-level luxury sedan introduced in 2003.

A company that has walked the sales/exclusivity tightrope well is Ferrari, Mr. Nerad said.

"They put out a car and it will be only out for a certain amount of time. Though the new car might have potentially a much longer model life, Ferrari limits that life and moves on to some other new model. ... Thus, there's always a new Ferrari that the superrich can covet and you don't have too many of any model out there," Mr. Nerad said.

Bentley officials say their secret weapon in the tug of war between sales and exclusivity is their factory. They once shared the Crewe plant with Rolls-Royce, which ended with the sale in 1998.

"We fully expect that the continual rise in sales volume will not continue because the capacity of our factory in Crewe is 10,000 units -- right about where we're at now. We have no plans to increase that in the near term," Mr. Reuter said. "We feel very comfortable with the volume where we are."