But is it really harder for emergency services to free a vehicle’s occupants from a car crash if the doors are locked?

According to RAA motoring expert Mark Borlace, it makes little difference.

“If your car is involved in a serious crash, often the vehicle will be structurally damaged to the point where it is unlikely the doors will open anyway,” Mr Borlace says.

Part of the ANCAP testing requirement is that the car’s doors should be able to be open after a 64km/h  impact has occurred.

This means there’s not much truth to the theory that it’s more difficult and takes longer to rescue occupants from the vehicle when they’re trapped inside with their locked doors.

“It’s likely one or more of the vehicle’s windows will be shattered by emergency services so that they can open the door that way,” he says.

“So, whether your doors are locked or unlocked is irrelevant, as emergency personnel are skilled to enter the vehicle one way or another.”

If you drive a newer car, you may not even have a choice in the matter. Why? Newer vehicles are often equipped with automatic locks, making it harder, if not impossible, to unlock the doors while the car is moving.

While it’s not a legal requirement to drive with your car doors locked in Australia, there are some states like Queensland and Victoria that have laws which stipulate the driver must lock their car if ‎they’re more than 3 metres from it.

In America, vehicle regulations require car doors to automatically lock while driving in a bid to combat carjacking.

There aren’t many modern vehicles in Australia which feature mechanisms that spontaneously lock the doors as soon as occupants are inside. This is more common in systems built to comply with the US regulations where they are required to lock at speeds over 25km/h. There’s also flashy car technology that can now unlock doors if, and when, the need arises.

“Most cars built in the past decade or more will actually automatically unlock the car after an accident if the vehicle detects that the airbags have been deployed,” Mr Borlace says.

Final word

If your car’s doors don’t automatically lock, RAA recommends drivers get into the habit of locking them manually for personal safety.