At around 5pm on Wednesday 28 June, a woman in her forties was driving her silver Mercedes estate on Southdown Road in the direction of Evesham Road, when another vehicle pulled in front of her car, causing her to stop.
The driver of the other vehicle, a silver Vauxhall Vectra, then exited his vehicle and approached the woman's car, which had its window open. He punched the woman several times through the open window, and then got back into his car.
The victim was not injured.
It is believed that the offender and the victim are known to each other.
The offender is described as a white man, in his early seventies, around 5ft 11ins and of a heavy build. He was clean shaven, with white hair and side burns.
Investigating officer, Detective Constable Emma Brooks, said: "This was a nasty attack and it was fortunate the victim was not seriously injured however she was understandably distressed by the incident.
“It is not believed to be a random attack, however we would like to speak to anyone who witnessed this incident, which took place at a busy time of day.
“It's believed a number of vehicles were caught behind these two cars which were blocking the road. If anyone in these vehicles or any other members of the public witnessed the offence, please call Thames Valley Police on 101, quoting incident reference 43170189997."