Police are hunting for the culprits who marked the sides of cars across Berkshire, Oxfordshire and Buckinghamshire, between March 12 and March 31.
Vehicles were targeted in areas including Newbury, Thatcham, Windsor, Bracknell, Slough, Henley, Milton Keynes, Oxford, Aylesbury and High Wycombe.
PC Samantha Hall said: "The nature of the offences has led us to believe that all of these incidents are connected.
"I believe that someone out there must be able to provide us with some information about who is responsible for this criminal damage, and I would urge them to come forward and speak to us as soon as possible."
Anyone with any information should contact PC Hall on the 24-hour non-emergency police number, 101, call Crimestoppers anonymously on 0800 555 111 or online at crimestoppers-uk.org