Executives face prosecution over failure to disclose likely financial damage to investors sooner.
France's No. 2 carmaker joined larger French rival Renault under scrutiny, but shares in both rose on reports of a bumper 2016 for European new-car sales.
Amid investigations into alleged diesel emission cheating, global automakers and regulators are struggling to define and comprehend shifting rules and enforcement from region to region.
President-elect Trump goes on the attack in a new series of media interviews.