“We are appealing for information following this incident.”
The victim sustained grievous bodily harm in the assault, and was taken to hospital but has since been discharged.
Police have just released details of the attack, which happened at about 21:15 BST last Sunday.
A force spokesman said following the motorway collision, which resulted in “minor damage”, the man had believed he was being pulled over by a police vehicle, but the car was not thought to have had any other markings.
The attackers were believed to have travelled in a red Nissan and dark-coloured Volvo.
Police are urging anyone with footage from the M40 or surrounding areas from about 21:10 to contact them.
