Volkswagen chief executive Martin Winterkorn apologized for the carmaker's cheating of diesel emission rules in the United States and pledged full cooperation with authorities involved. (Reuters)

Embattled Volkswagen chief executive Martin Winterkorn resigned Wednesday, less than a week after an emissions-cheating scandal erupted in the United States and quickly spread around the world, leaving the German car giant at risk of billions of dollars in fines and criminal prosecution.

VW acknowledged this week that 11 million of its vehicles worldwide, including nearly 500,000 in the United States, were involved in a deception that allowed the vehicles to pass emissions tests while emitting nitrogen oxide at up to 40 times the federal standard.

“I am shocked by the events of the past few days. Above all, I am stunned that misconduct on such a scale was possible in the Volkswagen Group,” Winterkorn said in a statement.

Winterkorn said that he took responsibility for the “irregularities that have been found in diesel engines,” but maintained that “I am not aware of any wrong doing on my part.”

Volkswagen didn’t immediately name Winterkorn’s successor, but the board will consider his replacement Friday, according to its executive committee, which includes top shareholders.

Volkswagen admitted to installing software designed to cheat emissions tests in about 11 million cars worldwide. While the cars passed emissions tests, they released nitrogen oxide up to 40 times the level allowed by federal law. Here's what you need to know about the scandal. (Jorge Ribas/The Washington Post)

In a statement released Wednesday, the committee said that it didn’t think Winterkorn knew about the software manipulation and it expects “further personnel consequences.”

Volkswagen’s public stock has shed 29 percent of its value since Friday, when the Environmental Protection Agency announced that the VW software, known as a “defeat device,” was installed in some 482,000 U.S. cars, spanning model years 2009 through 2015. Its stock climbed 7 percent Wednesday.

“In the view of the Executive Committee, criminal proceedings may be relevant due to the irregularities,” the committee said in the statement, adding that Volkswagen will cooperate in those investigations.

The potential cost of the scandal to VW is still spreading. It could be subject to up to $18 billion in fines from the EPA and is under investigation by the Justice Department. Government officials in Germany and other parts of Europe have launched separate probes. The company said earlier this week that it had set aside more than $7 billion to fix the problems with its cars and begin to repair its reputation with customers.

“This is going to cost the company a fortune, and that’s not what’s supposed to happen under a CEO’s leadership,” said Charles Elson, director of the University of Delaware’s Weinberg Center for Corporate Governance.

For owners of VW diesel cars, Winterkorn’s resignation offered little solace. Drawn by the promise of an environmentally friendly car, some now fear that the cars’ tarnished reputation will weigh on resale values. And since VW has not yet said how it will fix the problem, it’s not clear how its cars’ fuel economy and performance will change.

“The CEO resigning, it doesn’t really impact me. I want to know what they’re actually going to do for all of these supposedly clean diesel car owners,” said Christa Mrgan, 34, of Portland, Ore.

She bought a 2011 Jetta SportWagen because it promised low emissions and enough room for her two kids. Now, she’s planning to buy a cargo bike this week.

“I don’t want this car,” Mrgan said. “It makes me feel sick that I’ve been driving this car for about four-and-a-half years and belching all these toxic fumes into the atmosphere.”

VW, which also owns the luxury brands Audi, Bentley, Bugatti, Lamborghini and Porsche, had been seeking to unseat Toyota as the world’s largest automaker; now, it faces questions of how it will be able to keep up in a fast-evolving industry.

Wednesday’s announcement marked a swift fall for Winterkorn.

An engineer by training and VW’s former research and development chief, Winterkorn, 68, was known for his detail-minded style after taking the helm in 2007, helping to foster the company’s image as a green automaker and setting its global ambition.

“His thoughts for the company permeated throughout the company,” said Jack Nerad, executive market analyst at Kelley Blue Book. “He had very strong opinions about what Volkswagen should be as a group, what its brand should be. He was very, very hands-on.”

In the aftermath of that failed corporate ouster, Winterkorn, who earned 15.9 million euros ($17.7 million) last year, was up for a contract extension from VW, according to the Associated Press, a deal that would have kept him at the helm until his retirement.

The company board had been expected to approve the deal at a meeting Friday. Now, the board will use that meeting to consider his successor.

“I have always been driven by my desire to serve this company, especially our customers and employees. Volkswagen has been, is and will always be my life,” Winterkorn said. “I am convinced that the Volkswagen Group and its team will overcome this grave crisis.”

Moore is a freelance writer.