Sussex Police has launched a new operation to tackle car crime in Chichester.
This comes after a spate of incidents in beauty spots and rural locations in the Chichester area, which police said continues to attract sightseers - and 'opportunist thieves'.
A police spokesman said: "Vehicles left unattended while owners go off to explore are a tempting target for criminals keen to get their hands on their contents or even to steal the vehicles themselves.
"But be aware of such activity, local police have responded with Operation Mini, aimed at thwarting thefts and catching those responsible."
According to Sussex Police, it recently placed an offender before the courts with help from neighbouring Hampshire officers, leading to his conviction for theft and 92 weeks' imprisonment.
The spokesman added: "A warrant was issued for the arrest of another defendant who failed to appear, and three others detained have been released under investigation."
PC Kieron Morgan, from Chichester Police, said theft from cars is a 'perennial problem'.
He added: "Efforts have been, and are being, made to deter and detect this type of criminality."
Police also reminded all motorists to ensure their vehicles are locked and secure whenever they leave them, and to remove all valuable items.
Anyone seeing suspicious activity around vehicles are asked to dial 999 immediately and ask for police.
The spokesman added: "Information can otherwise be forwarded online, by calling 101 or contacting Crimestoppers.
"The independent charity can also be telephoned anonymously on 0800 555 111."