VW in particular is still struggling to come to terms with the so-called "dieselgate" scandal which erupted in late 2015 after it admitted to fitting millions of diesel engines worldwide with software to distort data on the amount of poisonous gases they were emitting.
But Der Spiegel said that the KBA vehicle licensing authority is now set to recall some Mercedes-Benz Vito vans produced by Daimler, as well.
Nitrogen oxides are poisonous, can contribute to acid rain and suffocating smog and can cause breathing problems and headaches in humans.
"We are in a technical exchange with the KBA," about the vans, a Daimler spokesman told AFP, saying around 1,000 of the 1.6-litre models were affected in Germany.
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Quoting transport ministry sources, Der Spiegel reported that officials in Berlin believe the software amounts to an "illegal defeat device", designed to cheat regulators emissions tests.
But Daimler denied any wrongdoing.
"We would take all legal means against the allegation of a defeat device," the Daimler spokesman said, while adding the firm would "continue to cooperate fully with the authorities".
VW also remains in officials sights.
KBA investigators have discovered "questionable" software functions in Macan SUVs produced by VWs subsidiary Porsche and could rescind the luxury cars licenses, Der Spiegel reported.