The man showed his disrespect for the law on the A1171 Dudley Lane in Cramlington while he was being driven in a black BMW X5.
The mooning passenger pushed his buttocks against the windscreen and was snapped as the powerful motor passed a mobile s
peed camera last month.
The driver, who appeared to be laughing on the snap, will not face prosecution because no driving offence was being committed.
But Northumbria Police will contact the car's registered keeper and could take action against the rude passenger for public order offences and not wearing a seat belt.
Jeremy Forsberg, of the Northumbria Safer Roads Initiative, said: "This behaviour is simply ridiculous.
"Aside from the danger of distraction, he is making a fool of himself.
"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.
"This passenger was disrespectful to the driver, other road users and the officer working to make the roads safer.
The Safer Roads Initiative is promoting the Road Respect campaign to make driving less stressful and safer."
He said: "We should all be sick and tired of reading about nonsense like this and more importantly tired of reading about another tragedy.
"So let's all take more responsibility for making the roads safer and better.
"I doubt any thought was given to the danger and offence caused by his stupid behaviour.
"It's clear he was thinking with what he had on show."
The full article contains 287 words and appears in News Guardian newspaper.
