Hidden cameras have been used as part of a new road safety campaign to show how some people react when they believe the person driving them is under the influence of drugs.
The Transport Agency hopes the advertisements will eliminate tolerance of drug driving in the same way previous campaigns have changed drink driving attitudes.
As part of the experiment, 147 people were recorded to see how they would deal with being the passenger of someone they were told had taken drugs.
One woman asked a driver who said he'd been smoking cannabis to stop the car, but other passengers seemed unconcerned.
The Drug Foundation says the difficulty in getting the message across is that some motorists actually believe drug taking improves their driving.