A motorist had his car damaged and was sworn and spat at after he tried to help another driver by telling him his headlights were not on.
The victim was travelling on the A17 at Clenchwarton, Norfolk, at about 0750 GMT on Wednesday when it was still partially dark.
He noticed the car behind did not have its lights on and when the two vehicles stopped side by side at traffic lights he wound down his window and told the car's passenger.
The man then responded by swearing and spitting in is face.
Registration clue
At the next set of traffic lights the same car - a grey Vauxhall Cavalier fitted with a tow bar - reversed into his vehicle causing extensive damage.
Norfolk Police have appealed for information to trace the Cavalier which may have had a registration starting "J6".
The car's passenger was described as white, in his mid-20s, wearing a dark hat and coat.
The driver was also a white male, about 40 years old, with heavy stubble. He was wearing a blue parka-style jacket.
A police spokeswoman said: "This was a shocking, unprovoked attack on an innocent motorist and we would appeal to the public to help us find these two men."