"We've had a whole range of reasons why vehicles are getting stolen that could have been avoided," he said.
"We've had people who have left cars unlocked with keys in the ignition. We had an opportunist case last week where a lady was loading her kids into the car [that was running], and the thieves took off with the car down the driveway.
"It's extremely rare, but there are some people who will do that outside the dairy, and it's just a matter of time before someone jumps in while the driver leaves their car idling while they run in to get some milk.
"Generally, [police] still battle with the public's apathy to security at times, and I always scratch my head."
Osland said the Tactical Crime Unit had investigated the cases and determined it wasn't one particular offender or group involved in the thefts.
"There's lots of stuff happening. Some cars are turning up in Palmy, a trailer was stolen and turned up in Carterton, and there's also the joyrider kid stuff," he said.
"Analysis of where the cars have been recovered and the way they have been stolen, our TCU believe its not one specific offender, and we think its been several different groups of offenders.
"It does go in peaks and troughs, but it's not one particular group."
Osland said to help this spike go down, the public would need to start taking some crime-prevention tips on board.
He said not leaving spare keys in the car, removing valuables, ensuring things were out of sight and setting the steering lock were measures people should take.
"We look for every forensic opportunity we can get, but we also need the public to be more mindful with their security," he said.
"Some people leave their spare keys inside the car, which they shouldn't do. A security measure nobody ever uses is locking the steering wheel. It makes it harder for [a thief] to overcome the ignition.
"If someone wants to steal your car and they've got time and an opportunity, then they'll do whatever it takes if they're that motivated.
"But you can make things as difficult for them as possible because the inconvenience of losing your car, the insurance, is painful."
