Patrols have been increased in south Northants after tools were stolen from vehicles in Brackley at the end of last week.
Nine vehicles were broken into overnight from Thursday to Friday and tools stolen.
A police spokesperson said: “This type of incident happens very quickly and does not give us much opportunity for investigation as usually there are no witnesses and little forensic evidence.”
Ideally, all items, including tools, sat navs, handbags, CDs and mobile phones should be removed from cars and vans when leaving them.
The police spokesperson added: “Our message is clear: Do not leave valuables in your vehicle, ensure it is locked, and if it has an alarm, use it. Similarly, if you have a garage, please use it.
“Whenever you park your car, whether it is in a public street or on your driveway, it is always worth taking a few seconds to remove items that are on show.
“It is also worth bearing in mind that even if you remove a sat nav from your car then a mark may have been left on the windscreen, so it is always advisable to remove any marks left behind.
“It is easy to fall into the habit of not parking your car in your garage, or not using a steering lock or the alarm system, but these quick and simple steps could be the difference in you becoming a victim of vehicle crime or not.
“If you do need to park your car in a public place and leave in unattended, make sure you park in a secure, busy area.”
People are also advised to be on the look-out for anyone acting suspiciously and to call police if they have any concerns.
Officers would like to speak to anyone who may have witness any suspicious activity in Brackley last week or anyone who may have been offered any tools for sale.
Witnesses or anyone with information is asked to contact police on 101 or Crimestoppers anonymously on 0800 555 111.