Many in Gothenburg, also in Falkenberg to the south and Trollhattan. Given then there are so many Saabs in Trollhattan, very likely some of the burned cars are Saabs.

In 2005, it seemed like 1/3 of the cars in Trollhattan were Saabs. So shocking! Now it's probably way down but the newest Saabs, other than a few exceptions are 7 years old.
(says 80 cars but a more recent reports cites 130)
Dozens of cars have been set alight in Sweden overnight, in what police say may be a co-ordinated criminal action.

Up to 80 vehicles were badly damaged by gangs of black-clad youths, beginning at about 21:00 local time (19:00 GMT).

Most of the damage took place in the western city of Gothenburg, but incidents were also reported in cities up to 100km (60 miles) away.

Prime Minister Stefan Lofven said: "It looks like very coordinated, almost like a military operation."

Cars were also damaged in Trollhattan to the north of Gothenburg, and Falkenberg to the south.