WOLFSBURG (Reuters) -- New Volkswagen Group Chairman Hans Dieter Poetsch said it would take time to get to the bottom of the automaker's rigging of diesel emissions tests.
More than two weeks after it admitted to cheating U.S. emissions tests, VW is under pressure to identify those responsible, to say how vehicles with illegal software will be fixed and whether it also cheated in Europe.
"Nobody is served by speculation or vague, preliminary progress reports," Poetsch told a news conference on Wednesday after being confirmed as the automaker's new chairman. "Therefore it will take some time until we have factual and reliable results and can provide you with comprehensive information," he said, declining to take any questions
VW named Frank Witter to succeed Poetsch as chief financial officer.
Poetsch addressed reporters after the carmaker's 20-person supervisory board met at its headquarters in Wolfsburg to discuss the progress of its internal investigation into the biggest business crisis in the company's 78-year history.
Poetsch, 64, said U.S. law firm Jones Day which is conducting an external investigation, the company was "leaving no stone unturned."
VW was due on Wednesday to submit a plan to Germany's KBA federal transport authority to spell out how it will make its diesel vehicles comply with emissions laws.
On Thursday, Volkswagen's top U.S. executive will testify before a U.S. congressional oversight panel.
Both events come as investigations and lawsuits against the company continue to pile up.
According to a letter released on Wednesday, top senators on the U.S. Senate Finance Committee are investigating Volkswagen's actions related to federal tax credits designed to reward consumers for buying environmentally-friendly vehicles.
VW has said it may have to refit up to 11 million cars and vans worldwide, and new CEO Matthias Mueller said in an interview with the Frankfurter Allgemeine Zeitung that recalls would start in January and would be completed by the end of 2016.
Owners are anxious to know whether the refits will affect the fuel-economy and performance of their vehicles.
VW has said the illegal software was not activated on the bulk of the 11 million vehicles, most of which are in Europe, leaving uncertainty over whether it rigged tests there.
The German KBA transport ministry has said VW manipulated European tests but has not given details, making it unclear whether the company faces the same level of fines and lawsuits in Europe as in the United States. It is also unclear whether owners will be obliged to have their vehicles refitted.
Equinet analysts said the cost of refits could range from less than 100 euros ($112) per vehicle to as much as 10,000 euros, depending on whether Volkswagen needs to upgrade software or install new hardware.
UBS analysts estimated the total bill for the scandal, including potential fines and lawsuits, could be around 35 billion euros, though they also noted this was more than factored into the company's share price after its recent plunge.
In his newspaper interview, Mueller rejected the suggestion Volkswagen informed financial markets too late about the test rigging despite having told officials at the U.S. Environmental Protection Agency weeks before it went public. "Based on our understanding of the law, we informed in time," he was quoted as saying.
He also said he believed only a few employees were involved in the manipulations.
In private, other German executives have expressed surprise at the appointment as chairman of Poetsch who, in his previous role as chief financial officer, would have had responsibility for deciding when to inform markets about the emissions rigging.
Germany's financial regulator Bafin has launched a preliminary probe into the circumstances around the announcement. Were it to determine that VW violated strict communication rules, Poetsch could come under scrutiny.
In the meantime, U.S. lawmakers are bound to press for detailed information on the emissions cheating. "We have a lot of questions. We have very few answers," complained Representative Diana DeGette of Colorado, the top Democrat for subcommittee.
Officials in Germany, where Volkswagen has been held up for years as a model of the country's engineering prowess, are also anxious for news. "I now expect a very transparent investigation of the circumstances. I am convinced that we will get more and more clarity," Klaus Mohrs, the mayor of Wolfsburg where Volkswagen employs around 70,000 people, told Reuters.
Some analysts and investors are worried company veterans such as Mueller and Poetsch will not introduce the sweeping changes in business practices they think are necessary to restore the company's reputation.
They are also concerned about the complexity of Volkswagen's investigations.