Cop stops Google car for driving too slow

San Francisco, - Google playfully posted a photo of a motorcycle cop pulling over one of it self-driving cars on Thursday for riding along at a cautious pace.

"Driving too slowly?" the self driving car team asked rhetorically in a message that accompanied a picture on its Google+ social network page.

"Bet humans don't get pulled over for that too often."

Traffic backing up

Police in Google's home town of Mountain View in Silicon Valley explained in an online post that an officer noticed traffic backing up behind a self-driving car going 38.6km/h on a street with a 56km/h speed limit.

The police department said: "As the officer approached the slow moving car he realized it was a Google Autonomous Vehicle. In this case, it was lawful for the car to be traveling on the street."

California law allows self-driving cars to operated on roads with speed limits of 40km/h or slower.

The officer did chat with the occupant of the car about impeding traffic, according to police.

Google caps the speed of its self-driving cars at 40km/h for safety reasons.

Google said of the speed cap on it driverless cars: "We want them to feel friendly and approachable, rather than zooming scarily through neighborhood streets."

"After 1.2 million miles of autonomous driving (that's the human equivalent of 90 years of driving experience), we're proud to say we've never been ticketed!"