One in 14 (7%) admit to driving at least once a month after taking drugs, according to a survey by Brake, the road safety charity, and Direct Line.
The survey also found that one in 12 people (8%) thought they had probably, or definitely, been a passenger, in the last year, in a car driven by someone who had taken drugs.
One in six people (16%) said they would get in a car with a drug-driver.
The release of these figures comes a year after the introduction of new drug-drive laws designed to make it easier for police to catch criminal drivers.
In the 12 months since the law change, there has been a six-fold increase in the number of convictions for drug-driving nationally, but some individual police forces have seen their arrest rates go up by 800%.
The latest official road safety figures available show 47 road deaths and 197 serious injuries in 2014 were caused when a driver was impaired by some kind of drugs. This was up from 21 deaths and 181 serious injuries in 2013.
But some estimates suggest around 200 people a year are killed on Britain’s roads by drivers on drugs.
Alice Bailey, campaigns advisor for Brake, said: “The hundreds of extra convictions over the last 12 months prove just how overdue this law change was. Different drugs have different effects, some slowing reaction times, others making drivers over confident and more likely to take risks, but they all have the potential to make drivers a danger to themselves and all other road users.
"The Government must make sure the police have the necessary resources to carry out these tests and keep catching dangerous drug drivers who risk killing themselves or someone else.”
Rob Miles, director of car insurance at Direct Line, said: “The significant increase in drug-driving convictions since the change in the law last year should serve as a serious deterrent to those considering getting behind the wheel after taking drugs. This is testament to how, when road safety issues are given due prominence, positive change can be achieved.”