Sgt. Michael Tryphonas said it's part of the department's ongoing effort to crack down on crimes.
"Especially with residential burglaries and robberies," Tryphonas said. "We've been doing a lot of special enforcement activities to reduce crime in the city."
Tryphonas was hesitant to name the types of vehicles police are using, since they are, after all, undercover.
The use of unmarked cars has caused some alarm from residents, concerned over whether they are getting pulled over by an actual police officer and not an imposter.
Tryphonas said that hasn't happened lately in Pleasanton.
"All the stories what we've seen through history is that they don't have badges, they just put up a red light," he said.
Still, he admits that it's not a bad thing for people to be suspicious if they're pulled over by someone they don't recognize as a police officer.
"You can always call dispatch at the police department's number, and ask them to confirm that it is a police officer," Tryphonas said. "Our officers always have badges with them and you can always ask to see their Pleasanton I.D. card."
The department's non-emergency number is 931-5100. But with little history of police impersonators in Pleasanton, he said odds are it's an unmarked car, with an officer just doing his job.
"We're doing everything we can to address crime in our city," Tryphonas said.