New cars, vans, light trucks and SUVsbuilt in Canada must be equipped with anti-theft engine immobilizers, Transport Canada has decided.

The new regulationwent into effect on Saturday.

Immobilizers are devices that prevent vehiclesfrom starting withoutkeys, thus preventing hot-wiring — starting a car's engine by bypassing the ignition system.

An engine with animmobilizer won't startuntil it recognizes a computer chip in the ignition key.

Owners ofvehicles with immobilizers can expect lower insurance premiums, butthose with higher-priced modelsshouldbe careful where they keep their keys after they park. Organized theft rings targeting luxury cars have been known tobreak into homes in search of keys to deactivate immobilizers, says Rick Dubin of the Insurance Bureau of Canada.

Auto theft costsCanadians at least $1.2 billion per year,taking into accountlegal and insurance costs, as well as health care for crime-related injuries, the insurance bureau says.

About159,000vehicles were stolen last year,a slight decline from previous years. About halfof them end up in "chop shops," where they'redismantled into parts to be sold off separately.

However,a Montreal-based auto-tracking company is questioning the effectiveness of the newregulation.

Boomerang Tracking Inc. says astudyit conductedfrom 2003-2007 showed 36 per cent of stolen vehicles the companyrecovered had Insurance Bureau of Canada-approved immobilizer devices.

Professional thieves will still be able to make off with cars by simply towing them or lifting them on toflatbed trucks,the company says.