Car thefts have halved in the past six years due mainly to the spread of vehicle immobilisers, according to a new study.

The report for the National Motor Vehicle Theft Reduction Council says the number of car thefts between 2000 and 2006 fell from 127,141 to 64,050. About 70% of stolen vehicles didn’t have immobilisers.

But thieves are still finding ways of getting around car immobilisers, as 23% of thefts involved cars fitted with an Australian Standards-approved device. More than half of all registered vehicles – and more than 80% of cars less than 10 years old – are fitted with an immobiliser.

The report says vehicles with an approved immobiliser are more than three times less likely to be stolen than those without. Immobilisers not meeting the standard only reduced the risk by about half.

And it appears non-approved immobilisers may be worse than no immobiliser at all – they’re more likely to be stolen that cars with no system at all.