The raids were part of an investigation into the sale of approximately 80,000 Audi diesel vehicles sold in the US between 2009 and 2015 that authorities suspected were outfitted with devices that enabled the company to cheat on emissions tests, Munich prosecutors said.
Stadler, who has run Audi since 2007, has been criticised for his handling of the emissions scandal but said on Wednesday he continues to command the VW board's full support, reiterated publicly last month.
The raids came as Audi CEO Rupert Stadler presented his company's 2016 earnings at its annual press conference.
The raids today focussed on who was involved in the use of any illicit software used in 80,000 VW, Audi and Porsche cars with bigger 3.0 litre engines.
Volkswagen has issued a global recall of all vehicles affected by the diesel manipulation and has pleaded guilty to conspiracy to commit fraud in the USA, agreeing to pay fines, penalties and consumer compensation of around $25 billion.
Cars sold in European markets are outside the scope of the investigation, the prosecutor said.
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Prosecutors in Munich have always been investigating whether the Volkswagen subsidiary could also be held responsible for the so-called Dieselgate scandal that erupted in 2015, when it emerged that 11 million cars worldwide had been equipped with software to deceive emissions tests.
The search included VW's Wolfsburg headquarters, along with Audi's Ingolstadt and Neckarsulm factories and six other unspecified sites, the group said. Offices and apartments are being searched but not the private home of CEO Stadler, the person said.
"There is still a long way to go before (dieselgate) is finally cleared up", Stadler told journalists at the firm's annual results press conference today.
This is the first raid of Audi since VW's diesel scandal broke out in 2015. "We will keep at it until this work is done".
Audi past year increased its diesel scandal-related provisions to 1.63 billion euros and has said it does not expect to have to do so again.