Editor's note: An earlier version of this report incorrectly stated the Eastern Daylight Time start time of Volkswagen's meeting. It has been corrected.
WOLFSBURG, Germany (Reuters) -- Hans Dieter Poetsch's first board meeting as chairman of Volkswagen on Wednesday could turn out to be his most important, coming just hours before a deadline set by German regulators and testimony by the company's top U.S. executive in Congress.
More than two weeks after the carmaker admitted to cheating U.S. emissions tests, Poetsch will be appointed to the helm of the 20-person supervisory board at a specially convened meeting at the German company's headquarters in Wolfsburg.
Sources close to the company say the meeting, due to start at 9 a.m. local time (3 a.m. EDT), is likely to last for hours, given the number and gravity of the issues to be discussed.
Europe's largest carmaker is under huge pressure to find those responsible, say how affected vehicles will be fixed and identify to what extent it may also have cheated in Europe.
The biggest business crisis in its 78-year history has wiped more than a third off Volkswagen's share price, forced out its long-time CEO and sent shockwaves through both the global car industry and the German establishment.
On Tuesday, more than 20,000 workers gathered at the company's sprawling Wolfsburg plant to hear new CEO Matthias Mueller address them for the first time since he replaced Martin Winterkorn two weeks ago.
"We will overcome the crisis," Mueller told staff, many of them wearing specially printed t-shirts with the slogan "one team, one family" to show their support for the company.
Mueller warned all projects and investments would be put under review and there would be "massive cuts."
But Volkswagen's ability to recover could also depend on what happens on two key dates this week: Germany's KBA watchdog has set a Wednesday deadline to submit a plan to make its cars compliant with emissions laws and the company's top U.S. executive is due to testify before a U.S. congressional oversight panel on Thursday.
Since Volkswagen's cheating was exposed on Sept. 18, the carmaker has come under fire for a slow response.
While it admitted on Sept. 22 that 11 million diesel vehicles worldwide were fitted with software capable of rigging emissions tests, it only provided customers with information about whether their vehicles were affected on Friday.
Owners have been told their cars and vans will have to be refitted, but do not know if this will affect their fuel economy or performance -- key issues that could determine the number of lawsuits and amount of damage to Volkswagen's reputation.
Analysts and investors are also anxious to know whether Volkswagen cheated emissions tests in Europe, too. The German transport ministry has said it did, but has not given details.
Given 8 million of the 11 million affected vehicles are in the European Union, any cheating there could have a bigger impact than the United States in terms of fines and lawsuits.
"We need clarity on Europe," Bernstein analyst Max Wurburton wrote in a research note this week.
"If the issue is just limited to the U.S. ... then the financial consequences may be containable. But if VW also cheated in Europe, then the situation will become much graver."
Who is reponsible?
Volkswagen's supervisory board will also be under pressure to come up with answers about who was responsible for installing the "cheat" software and concealing its usage.
The company has suspended more than 10 senior managers, including three top engineers. However, one source close to the supervisory board told Reuters on Monday the carmaker's internal inquiry had not found any evidence to accuse the top engineers of the manipulation.
Volkswagen has said its investigations, including an external one by U.S. law firm Jones Day, would take months.
But a panel of U.S. lawmakers will want answers when they question the company's U.S. boss Michael Horn on Thursday.
Two sources close to the board said Wednesday's meeting would look to provide Horn with detailed information and a timeline on the rigging of U.S. emissions tests.
CEO Mueller and an official from Jones Day will attend the supervisory board meeting, sources said.
Return of Piech
The rise of both Poetsch and Mueller signal a return to influence for Volkswagen's long-time chairman Ferdinand Piech, who was ousted in April after he publicly criticized Winterkorn's performance.
Piech, a member of the Porsche-Piech clan that owns a controlling stake in the German carmaker, has supported both managers in their careers.
The 78-year-old, who considers Volkswagen his life's work, was likely to exert renewed influence under the new regime in areas such as brand management and model strategy, a source close to the matter said.
After keeping away from the company in the months after his ouster, Piech and his wife Ursula visited the Volkswagen stand at the Frankfurt auto show on Sept. 22, four days after the emissions scandal broke and the day before Winterkorn resigned.
Some analysts and investors have questioned Volkswagen's decision to appoint company insiders to top jobs in the wake of the scandal, saying hiring outsiders would underscore its commitment to change.
Shareholder advisory firm Hermes EOS said last week it had "real doubts" about whether Volkswagen's main stakeholders recognized the need for fundamental reform.