The damage, which police believe to have been caused by another vehicle, happened between 16:00 on Saturday 12 September and Monday 14 September.
The Skoda was parked next to the motorcycle bay in Valnord Road – the road between Victoria Road and Mount Durand – at the time.
Police are appealing for anyone with information or who witnessed this to contact PC 62 Jordan Flatres.
He can be contacted by calling the police station on 725111 or by emailing Jordan.flatres@guernsey.pnn.police.uk. Alternatively, people can call Crimestoppers anonymously on 0800 555 111.