At least 12 cars were torched in Berlin overnight Thursday to Friday, making it the fourth consecutive night such arson attacks have taken place, police said.
German Chancellor Angela Merkel expressed shock Thursday at these attacks, which officials attribute to apolitical vandalism.
Berlin Mayor Klaus Wowereit has called for help from the public to help end the destruction.
"This is a case of pure vandalism and criminality," Wowereit told reporters.
He called on Berliners "to help arrest the culprits by reporting suspicious activity to the police".
Police have offered a $7 200 reward for information leading to the arrest of the perpetrators.
They believe the arson attacks are more likely the work of vandals than of politically motivated activists.
The total number of cars set ablaze in the capital this year stands at 159; 75 of them this month alone.
"We don't rightly know the reason for it," police spokesman Guido Busch told AFP.
"But we believe it is mostly the work of a single person, or a single group of people, and that it is vandalism with no political motive," he added.