The man told police he had originally planned to detonate the practice grenades – which are used by Bundeswehr soldiers in training exercises – on a New Year's Eve, when Germans traditionally embark on an orgy of fireworks lighting.
He was pulled over for a traffic check in the North Rhine-Westphalia city and aroused police officers' suspicion that he had taken drugs. During a search of the car, the police found a rucksack containing drugs and one of the grenades. They found the second explosive in the pocket of one of the car's doors.
The police alerted a bomb disposal expert as the grenades - which contain a smaller amount of explosives than normal grenades - could have caused serious injury if wrongly handed. Possession of such explosives is illegal outside of the Bundeswehr.
The 30-year-old claimed not to know this. He got the grenades several years ago, he said, from a member of the Bundeswehr personnel, whose name he did not know. Having not got around to detonating them on New Year's Eve as planned, he had instead driven around for several years with the explosives in his car.
He was charged with weapons and drug offences as well as receiving stolen property.