The vehicle was parked at the Watermead Inn when red paint was thrown on it.
Police would like to speak to a man who went into the pub and said that damage was being done to a car outside by a group of youths.
PC Kirstin Harding said: “We are keen to hear from this key witness to establish who is responsible for the damage to this car.
“They will be able to provide with us some vital information to aid police enquiries in relation to this incident.”
The incident was at about 3.15pm on May 28, police said today.
Anyone with information should call police on 101 and Crimestoppers anonymously.