DENVER -- 7NEWS Investigators are exploring accusations of a seven-year cover-up by a major automaker -- an automaker known for building the safest cars in the world.

7NEWS' Investigator Tony Kovaleski has obtained key documents that raise serious questions about Volvo's commitment to safety. Our investigation includes a discovery by a Colorado man that may ultimately force Volvo to recall hundreds of thousands of cars worldwide.

Virginia Callahan owns a 2000 Volvo XC. She had a problem with her vehicle last Thanksgiving on the highway from New Mexico to her home in Fort Collins, Colo.

"We'd get out in the left lane and press the accelerator and we'd lose power," said Callahan. "It would just shudder as if it didn't have enough juice to go."

Like many others, she had no idea what caused the problem.

"I was freaked. I was very scared," said Callahan.

Callahan said that she felt that the car put her and her husband at risk. And she's not alone. The National Highway Traffic Safety Administration has received more than 130 similar complaints citing a complete stall without warning, sudden loss of power and unexpected accelerations.

"You go from being a driver in traffic to being a target in traffic. I don't know how to put it any plainer," said longtime Volvo owner and retired engineer Don Willson.

Willson has spent months researching the cause of the problem.

"It's inevitable that somebody is going to be seriously hurt," he said.

He discovered the problem on his son's Volvo -- a car that his teenage granddaughters will drive. He believes the failure comes from the electronic throttle module, which is similar to the old carburetor. It controls fuel flow and ultimately the car's power.

He believes the problem is in the throttle position sensors.

"This should never fail," he said.

But complaints from people in at least 24 states and 12 countries say that it is failing on a regular basis. People from around the world have contacted 7NEWS Investigators about the problem.

Frank Hanson of Wisconsin described pulling into an intersection and said, "The car would barely move even though the accelerator pedal was fully depressed. I was left broadside against two lanes of oncoming cars."

Hanson was told the electronic throttle system had to be replaced at a cost of $1,200. Virginia Callahan's problem cost nearly $900 to fix.

"At that point, I thought, 'Wait a minute, what's going on here?'" Callahan said.

Experts estimate worldwide that there are approximately 300,000 to 400,000 Volvos with this particular throttle assembly.

"Considering my granddaughter's life depends on that part ... I know that is the problem," said Willson.

Apparently, Volvo knew it as well. 7NEWS Investigators obtained internal documents where Volvo clearly indicates the company was aware of failures with the throttle assembly back in May 1998.

"There has been an increase of faulty throttles from the car plants the last three to four months," according to the documents.

"It's one of the biggest defects I have ever seen and we have looked at a lot of defects," said consumer right attorney Dina Micheletti.

Micheletti has launched a class action suit in California against Volvo -- a company that's built it's reputation on safety.

"It stands to reason that the people who bought the cars thought, first and foremost, they were getting a safe vehicle. They're not here," said Micheletti.

An internal Volvo document details a disturbing discovery about the electronic throttle modules (ETM). It said the company's own research projected a failure rate of 94 percent in some models at or before 100,000 miles.

"Less than 1 percent is enough to cause alarm and enough to trigger a recall. We have projected failure rates that go as high as 94 percent within the life of the vehicle. It's absolutely astronomical," said Micheletti.

Although Volvo said that it's cooperating with the federal investigation, the company has declined 7NEWS' request to explain its side on camera. The company declined to explain why it has not recalled the electronic throttle module and declined to explain the contents of the documents cited in 7NEWS' investigation.

"I think that cover-up is probably an appropriate word to describe the situation," said Micheletti.

For Willson, Volvo's documents are further confirmation of the internal secret he's suspected all along.

"They've known about the problem for five years and, as yet, have not told the dealers what the problem is," said Willson.

He said he considers that a cover-up.

"They don't want to face the facts," said Willson.

It's an accusation leaving thousands of car owners such as Callahan wanting Volvo to reinforce its global reputation for safety.

"I really hope that Volvo does the right thing," Callahan said. "They need to do a recall."

The particular electronic throttle module is on all gasoline-powered Volvos from 1999 to 2001 in the 60, 70, and 80 series.

So why hasn't Volvo done a voluntary recall? Willson believes the reason is money. To do work on 400,000 cars at nearly $1,000 a piece adds up to 400 million reasons not to do a recall.

Do you have questions or comments on this story? E- Mail Tony Kovaleski or 7NEWS Investigators.

Additional Resources:

VexedVolvo.org
National Highway Traffic Safety Administration
Volvo