The arsons happened early Sunday morning on the city's east side.
Investigators believe the suspect was able to get inside each car, before lighting it on fire. What they don't know is a motive.
"There's no sort of commonality that links these cars together, or suggests any reason why these cars were attacked. There were a number of other vehicles, both parked in driveways and out on the street in front of these homes, and so there's nothing to indicate any specific reason why these might have been targeted," says Santa Cruz Police Capt. Steve Clark.
Police are now looking for clues inside the burned out vehicles.
One of the first things they are trying to determine is the type of accelerant that the arsonist used.