You come out of the store and your car has been stolen.

What do you do? Call the police? Call home?

If you own a General Motors vehicle with OnStar, you may be able to make one call that won't just locate your car, but notify police who then can work with On Star to slow it down to a crawl once the police have zeroed in.

Recently, GM demonstrated a new technology, called Stolen Vehicle Slowdown, that helps in the safe recovery of subscribers' stolen vehicles. Stolen Vehicle Slowdown sends a signal to a subscriber's stolen vehicle to reduce engine power, slowing the vehicle down gradually.

GM Canada and Metro Toronto Police showed how the system works at 23 Division in the Rexdale part of the city.

In jurisdictions where police and OnStar have agreed to work together, the process goes like this.

• Once the vehicle has been reported stolen to law enforcement, the subscriber calls OnStar and requests Stolen Vehicle Location Assistance.

• OnStar uses real-time GPS technology to pinpoint the exact location of the stolen vehicle and provides this information to law enforcement officials to help them recover the vehicle.

• When law enforcement has established a clear line of sight of the stolen vehicle, law enforcement requests OnStar to slow it down remotely.

• Safeguards are in place to ensure that the correct vehicle is slowed down. The vehicle's parking lights will flash so that law enforcement can verify they have located the vehicle and that it is safe to slow the vehicle.

• OnStar then sends a remote signal to the vehicle that interacts with the Powertrain system to reduce engine power, which slows the vehicle down gradually.

There was great debate during the planning of the system whether or not to lock the thief in the car until police arrested him/her but it was decided the better course was not to engage the locks.

GM said the Stolen Vehicle Slowdown is an enhancement to OnStar's Stolen Vehicle Location Assistance, which has actually been available since 1998. Stolen Vehicle Location Assistance uses Global Positioning Satellite technology to pinpoint the location of a vehicle that has been reported stolen. OnStar provides the location to law enforcement to assist with the vehicle's recovery.

There are a lot of variables. For instance, you, somehow, have to remember the OnStar number and your PIN number. And it is currently available only on the Buick Lucerne, Saturn VUE and most of GM's big trucks and SUVs, but that is supposed to expand as the new generation OnStar is included with new vehicles.

As a GM new vehicle buyer you have to decide if you want the service or not. You will have the choice to opt-out of the Stolen Vehicle Slowdown service at any time by contacting OnStar. This will not affect the rest of your OnStar services.

OnStar's Stolen Vehicle Slowdown is a GM-exclusive feature in Canada and the U.S. and is included in the one-year OnStar subscription that customers receive when purchasing an eligible MY 2009 OnStar-equipped vehicle.

Depending on how much you want to pay, OnStar's lineup of services also includes Advanced Automatic Crash Notification, Emergency Services, Remote Door Unlock, Roadside Assistance, Crisis Assist, OnStar Turn-by-Turn Navigation, Hands Free Calling and OnStar Vehicle Diagnostics.

If you are interested in this new anti-theft service and want more information, visit Northstar Motors Cranbrook.