Volkswagen's share price opened higher this morning after embattled chief executive Martin Winterkorn resigned yesterday afternoon in the wake of the emissions cheating scandal.
Winterkorn, who has been at the helm of the car giant since 2007, said he had been "shocked" by the scandal - but insisted he knew nothing about the "misconduct".
Robert Clifford, partner at Clifford Law, said the lawsuit had been filed at a district court in northern Illinois. The complaint was filed on behalf of two Volkswagen owners, who said they would not have bought the vehicles if they had known they were not environmentally friendly.
Volkswagen is expected to face a criminal investigation in the US, as well as other probes in France, Germany and South Korea.
The scandal has wiped billions off Volkswagen's value since the start of the week, although yesterday its share price closed up more than five per cent.