A driver has been fined a little more than AU$500 after police realised one strange detail about their passenger.

The motorist was pulled over in the carpool lane in Baldwin Park, California on February 19 and California Highway Patrol noticed that the driver’s “passenger” was indeed not a passenger at all.

They quickly realised it was actually a dummy that was put in the passenger seat and fully dressed in a flannel T-shirt, glasses, a Cleveland Indians baseball cap and none other than a face mask.

“By far, one of the best dummies we have ever seen,” police said.

“To clarify, we are referring to this fake passenger.

“At least he was following CDC guidelines by wearing his face mask.”

Officer Rodrigo Jimenez told the San Gabriel Valley Tribune that the driver “didn’t say much”.

“Other than that he’s been driving with the mannequin, and he’d been getting away with it for a year and a half,” he revealed.

The driver had a dummy beside him to show he had a passenger so he could use the carpool lane.

It is illegal in several US cities to use a carpool lane with only just the driver in the car.

The fine was around $514, however the driver was allowed to keep the dummy.