Almost 7,800 people were arrested on suspicion of driving while under the influence of drugs in England and Wales during the 12 months to April, figures obtained via Freedom of Information requests show.
Although data was obtained from 35 police forces, eight did not supply their figures and the RAC points out that its research suggests more than one in 20 motorists may have driven after taking drugs.
The figures - supplied to BBC Radio 5 Live - show the Metropolitan Police made more arrests (1,636) than any other force.
A further 573 motorists were arrested by Greater Manchester Police with officers in Cheshire arresting the third highest total (546).
Police were issued with testing kits after new legislation was introduced to target those driving under the influence of eight illegal drugs and eight prescription drugs.
The kits enable officers to screen motorists for cocaine and cannabis at the roadside. The presence of other drugs such as heroin, ecstasy and LSD can be tested for at a police station.
For some forces the introduction of the test and the legislation has had a huge impact on the number of arrests.
South Yorkshire Police, for example, saw drug driving-related arrests go up from 13 in the year the test was introduced to 456 the following year.
Pete Williams, the RAC’s head of external affairs, says: “We suspect that these conviction rates may well understate how widespread drug-driving is - this could represent the tip of an iceberg.
“The RAC’s Report on Motoring 2015 revealed that 6% of motorists admitted to having driven under the influence of drugs in the last 12 months, whereas in 2014 the rate was just 2%.
“This may be because the introduction of the new drug-driving legislation has increased awareness of the prescription drugs, including sedatives and stimulants, which are now outlawed.
“It is also a challenge for the police to detect and enforce the law. The number of full-time dedicated roads policing officers has dropped by 27% since 2010 to fewer than 4,000 across England and Wales.
“While offences like speeding and running a red light can be captured by cameras, when it comes to drug-driving there is no alternative to a physical police officer to detect and enforce the law.”