Former chief executive of Volkswagen Group on Wednesday said the charges against him were "implausible" as he testified at his trial over the "dieselgate" scandal that rocked the German auto titan.

"I think it is implausible to make a criminal accusation against me like (prosecutors) are trying to do with their charges," Martin Winterkorn told the court in the German city of Braunschweig, close to VW's historic Wolfsburg headquarters.

The 77-year-old went on trial Tuesday, nine years after Volkswagen admitted installing software to rig emissions levels in millions of diesel vehicles worldwide, setting off one of Germany's biggest postwar industrial scandals.

Previous attempts to bring him to court had failed due to his poor health.

But now he is facing charges, including fraud and market manipulation over the so-called defeat devices, which made cars appear less polluting in lab tests than they were on the road and could be jailed for up to 10 years if convicted.

Winterkorn denies all the allegations.

In a lengthy statement, he described how he headed a sprawling corporate empire, had numerous responsibilities, and was far removed from detailed decision-making.

The ex-executive conceded that, due to being boss of the carmaker when the scandal erupted, he would always be "closely linked" to "dieselgate."

But he added: "I was not involved in the decisions on the development and use of this irregular software function in the new VW diesel engines."

Winterkorn was CEO of Volkswagen – whose brands range from Porsche and Audi to Seat and Skoda – from 2007 until 2015. He resigned shortly after the scandal began.

Winterkorn's attorney, Felix Doerr, said ahead of court proceedings on Tuesday that "our client definitively rejects the accusations brought against him." He said that Winterkorn's position as CEO was not justification to make him responsible for the scandal in all its aspects.

He was scheduled to go on trial in 2021 with four other VW executives, but his case was postponed due to health issues.

Winterkorn vigorously defended his track record as head of Europe's top automaker, saying profits rose fivefold when he was in charge and the number of the group's staff nearly doubled to over 600,000.

"I have dedicated almost my entire professional life to the Volkswagen Group and have tried for decades to develop good cars and sell them to our customers at fair prices," he said.

And he insisted that, while the reputation of diesel cars had been impacted by the saga, that of VW "has not been permanently damaged."

'Not an engine developer'

Much of the prosecution's case centers on proving that Winterkorn knew about defeat devices earlier than he has admitted. But he insisted such claims were "not correct."

"I am not an engine developer, I am not an emissions control specialist and I am not a software expert," he said.

The principal charge of conspiracy to commit fraud relates to about 9 million vehicles sold in Europe and the United States, with the buyers facing financial losses running into hundreds of millions of euros, according to the court.

However, Winterkorn has not been accused of involvement in the offense for its entire period, which was from 2006 to 2015.

He was also accused of giving false testimony to a German parliamentary committee in 2017 when it was investigating the scandal.

Winterkorn further faces a charge of market manipulation for allegedly failing to inform the markets "in good time" after finding out about the emissions-rigging software, which violates German stock market regulations.

Questions about Winterkorn's health hang over the proceedings, with reports saying he had to undergo an operation in mid-June. Some 89 hearings have been scheduled through September 2025 in the complex case.

The fraud indictment alone stretched to 692 pages, including the other four defendants, while the case file consists of 300 volumes with 75,000 pages of supporting documents.

Prosecutors alleged in their indictment that Winterkorn learned of the issue at least by May 2014 but continued to permit the practice and allowed rigged cars to be sold. They say that the software appeared in Volkswagen cars in Europe and the U.S. as early as 2006.

Winterkorn had already agreed to pay Volkswagen 11 million euros ($12 million) in 2021 as part of a settlement.

The highest-ranking former executive to have been convicted so far in the scandal is ex-Audi CEO Rupert Stadler, who received a suspended sentence and fine last year in exchange for admitting fraud.

The diesel scandal had wide-ranging consequences for the company and the auto industry.

Volkswagen has already paid more than $34 billion in fines, legal costs, and compensation to car owners, mainly in the U.S. Sales of diesel-powered cars, once favored for their fuel efficiency over gasoline-powered vehicles, plunged as a share of the car market in Europe.