A man was attacked after being pulled from his car as it sat at a junction on Sunday afternoon.
The 28-year-old was punched to the head several times on Newport Road at the junction with St Peters Way in New Bradwell at around 4pm.
The victim who was driving a red Vauxhall Corsa was left with two black eyes, but did not require hospital treatment.
His attacker, who is a white man, fled the scene in a black Vauxhall Zafira.
There is no further description of him at this time, police say.
PC Tom Hughes said: “This assault occurred in broad daylight, so I am sure there will be witnesses to the incident.
“If you saw either vehicle in the vicinity of Newport Road at the junction with St Peters Way in New Bradwell or have any other information then please call police via 101.
If you don’t want to speak directly to the police you can contact Crimestoppers anonymously on 0800 555 111 or online at www.crimestoppers-uk.org.
No personal details are taken, information is not traced or recorded and you will not go to court.
> A 28-year-old man from Milton Keynes has been arrested on suspicion of assault. He has been released on police bail until July 23.