Safety campaigners have labelled the man as a "fool"
A front seat car passenger was photographed baring his backside at a speed camera in Northumberland.
The "mooning" man was snapped by the mobile camera as the black BMW X5 drove past on the A1171 Dudley Lane in Cramlington last month.
His behaviour has been labelled as "dangerous and offensive" by road safety campaigners.
Police may take action against the man for public order offences and not wearing a seat belt.
Officers have the registration of the car, which was not breaking the speed limit, and intend to contact its owner.
It is understood the driver will not face prosecution as no driving offence was being committed.
Jeremy Forsberg, of the Northumbria Safer Roads Initiative, said: "This behaviour is simply ridiculous - it's clear what he was thinking with what he had on show.
"Not only is it disrespectful, but distasteful and offensive, particularly to children who may have been exposed to this nonsense.
"This prank could have been a real distraction from the driver and that is not something to laugh about."