SAN FRANCISCO — The World Touring Car Championship has a noise problem — as in, there may not be enough of it.

"We're not very noisy cars," said Englishman Tom Chilton, one of the 20-plus drivers who will line up for the start of a pair of 13-lap races at the raceway in Sonoma on Sunday. "We've got 1.6-liter engines. We're running this new world engine, which is fantastic and it's really, really good, but as an American goes, they might be thinking this isn't as noisy as NASCAR or anything like that."

The WTCC is a popular circuit, with (according to the organization) upward of 40 million viewers watching its races on more than 80 channels across the globe. But some serious questions surround its United States debut: Are touring cars loud enough? Are they big enough? Are they American enough?

"It's a big challenge, I have to say," WTCC general manager Marcello Lotti said at a news conference in San Francisco on Wednesday. "... Because in America, motorsport world is represented by NASCAR, by Indy. It's something that is really a completely different concept."

The touring-car concept is built not so much on raw power as agility and competitiveness.

The cars are fast enough — they will crack 100 mph on Sonoma's limited straightaways — but nothing like an open-wheel vehicle. Every touring car has a four-cylinder, 1.6-liter engine with a restrictor plate and a six-speed sequential gearbox. They all weigh roughly the same, and are within 5 to 10 horsepower of one another, which makes for some crowded lanes.

"Bumper-to-bumper racing — very close, very tightly fought sprint races," said Rob Huff, who drives the Chevrolet Cruze car and is currently in second place in the WTCC standings. "I think 25, 26 cars on the grid, all qualifying within sort of a second to a second-and-a-half of each other."

The parity, along with the touring cars' maneuverability and the brevity of the races, has attracted followers in far-flung corners of the world.

The WTCC's European season included stops in Italy, Spain, Morocco, Slovakia, Hungary, Austria and Portugal. It just went to Brazil following a two-month break, and after Sonoma will head to Japan, China and Macau.

Lotti said that Japan, China and the U.S. were the three nations that had been at the top of the WTCC's wish list. It got to Japan last year. China, like America, makes its debut this year.

Once the series and its umbrella organization, FIA, believed an American race was feasible, they had to select the right track.

WTCC executives soon began focusing on the West Coast, and especially California, because of its marketing opportunities and its greater acceptance of European-style racing. (Translation: The Pacific coast isn't as dominated by NASCAR culture.)

The early front-runner was Raceway Laguna Seca outside of Salinas. Laguna Seca is a renowned MotoGP motorcycle racing track and, as Lotti explained, good MotoGP courses tend to be good touring-car courses.

But a promoter for USTCC, the fledgling American spinoff of the WTCC, said to Lotti: "Look, Marcello, do you know Infineon Raceway?"

Lotti admitted he did not. Hhe took a trip to Sonoma to scout the raceway formerly called Infineon, and was smitten.

"When I saw the track, I said, &‘This is the track for touring car,'" Lotti recalled.

Chilton, who pilots the Team Aon Ford Focus, agrees. He has raced at Laguna Seca on three occasions in the American Le Mans Series and likes it a great deal.

"Now, coming to Sonoma, I'm like, &‘Whoa, I prefer Sonoma.' It's a lot better," Chilton said. "It's like Laguna Seca times four. Because you've got two massive steep hills, where the cars are gonna be awesome on the limit, and some curves, which could get some good two-wheel action. And then you've got two really dramatic corners."

While the WTCC drivers seem pleased about racing at Sonoma, and about spreading the word to America, no one is sure if the love will flow both ways.

Americans are a bit set in our stock-car ways when it comes to motorsports. Even IndyCar struggles for attention here — and IndyCar has some made-in-the-USA drivers. Of the 30 men currently competing on the WTCC circuit, none is American.

Lotti said the organization isn't expecting any miracles right off the start line.

"Sunday we will know," he said. "We cannot dream to have 50,000 or 30,000 spectators the first year. We have to be conscious of this Sunday evening, and work properly and improve for the second year."

He has learned to keep an open mind. Last year, when the series debuted in Japan, the presale figures were a disaster — about 500 tickets. On race day, Lotti woke up to rain and felt like pulling the covers over his head. But a good walk-up crowd bumped the attendance to 24,000.

How long will it take touring cars to build a following in the United States?

"How long's a piece of string?" Chilton said, meaning there is little to do but unspool these races and see where they lead.

You can reach Staff Writer Phil Barber at 521-5263 or phil.barber@pressdemocrat.com.