A team of 20 police cadets hit the streets of Ilkeston last week in a bid to raise awareness about unlocked vehicles.
The group, together with police officers, checked to see if cars were unlocked and then spoke to owners about crime prevention.
Letters will be sent to vehicle owners who were not available to speak to at the time.
They covered the Lord Haddon Road, Kirk Hallam and Kniveton Park areas on Thursday (October 3) after recent reports of car crime.
Over two hours, 188 vehicles were checked with 36 vehicles found insecure or with property clearly on display such as sports bags, sat navs, iPods and cables.
Pc Dave Keane said: “The people committing these crimes are looking for an easy opportunity to take things they can sell on quickly.
“Why give an opportunist thief the chance of taking something of yours and causing a lot of upset and inconvenience?
“We hope that through our efforts we were able to educate local residents on security measures they can employ to keep their vehicle and belongings secure.”