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Former Volkswagen CEO Martin Winterkorn said Wednesday 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," he 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 post-war 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.

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