Since Christmas Eve there have been 19 thefts from vehicles in Halifax - including eight from taxis and private hire vehicles.
Police are now urging motorists to remove valuables to avoid being a victim of crime.
Inspector Colin Skeath said officers were actively speaking to drivers to advise them on crime prevention tactics. The offences have been happening overnight, with peaks between midnight and 5.30am.
“Thieves tend to be opportunistic and will look for the easiest available option,” said Insp Skeath.
“We are doing all we can to stop criminals in their tracks and officers are always on patrol keeping a watchful eye out – but we need people to work with us and make life more difficult for thieves.
“Officers have been astounded to see valuable items including laptops, wallets and mobile phones on show. You wouldn’t leave these things outside on your wall – and the same goes for your vehicle.”