More drugged drivers are being caught in Bay of Plenty than any other region.
A total of 139 people in the Bay of Plenty, mostly from the Western Bay, have been charged for driving under the influence of drugs since the introduction of an anti-drug-driving law in November 2009.
But Automobile Association spokesman Dylan Thomsen said if police in other districts were carrying out the same number of tests the results would likely be much the same.
"The police in the Bay of Plenty have actually made this a focus and have been doing more tests. I would say it's a credit to the Bay of Plenty police that they are targeting the issue but it's just the tip of the iceberg."
A breakdown of police figures showed 88 of the drugged drivers caught in the Bay of Plenty had THC (cannabis) in their system, 29 had stimulants, four had opiates, and three had sedatives.
Nationally, 453 drivers were drug tested in hospital after a crash that was deemed to be their fault and 156 of them were found to have drugs in their system.
Mr Thomsen said the figures showed drug-driving was an epidemic: "I think when you look at the latest figures, there's no other way to describe it."
Senior Sergeant Ian Campion said the issue was bigger than people realised.
"You only have to look at the stats.
"We are by far the leading district for the whole of the country, which is an unenviable reputation to have because obviously to produce that many ... we do have a drug-driving problem," Mr Campion said.
"We've got more of a problem with drug-driving than everybody perceives and, of course, the biggest concern is that even a small minority of drugs in the system coupled with alcohol can exacerbate the potential danger."
The lack of police ability to test for drugs before the law change may have created a casual attitude towards driving while drugged, he said.
"There probably has been a blase attitude towards it because of the lack of enforcement around the issue."
In a breakdown of ages, people aged between 20 and 39 years represented more than half of all people in the region charged with drugged driving.
A total of 174 people have sat the compulsory impairment tests (CIT) in the Bay since 2009.
Bay of Plenty road policing manager Inspector Kevin Taylor said in April, there was no denying the region had a significant drug problem.
Mr Taylor referred to a large Western Bay drug operation where police netted $2.7 million worth of drugs earlier this year.
The 139 drivers charged compared with 81 charged in Waitemata, which had the second-highest rate.
Nationwide police have charged 694 people for drugged driving.
Most were men.
The Automobile Association this week renewed its calls for random roadside saliva tests to be used to target drug-drivers.
Such saliva screening devices can detect only three drugs - cannabis, methamphetamine and Ecstasy - and are used in every Australian state.
But Tauranga MP and Associate Minister of Transport Simon Bridges said saliva testing technology would need to improve before the Government considered using it.
A government review of the drug testing regime in May concluded the testing devices were not reliable or fast enough.
AGE BREAKDOWN OF BAY'S DRUGGED DRIVERS
- 20-24 years - 21.5 per cent
- 25-39 years - 33.8 per cent
- 40-59 years - 24.4 per cent
- 60-74 years - 0.7 per cent.