The figures for Northland follow a similar national trend where nearly half or just over half of learner drivers are failing their restricted licence tests.
Ms Mahanga said she had been gutted and burst into tears after failing her restricted driving test four times over the past three years.
"I wasn't the only one. Others were coming away from their tests crying too," she said.
She paid $130 for her first test, which the testing official had refused to carry out because the car she was using had a dim stoplight. Her second attempt had failed because the driving course she was on had failed to provide a car in time for her test. A different course prepared her for her third attempt, in which she had failed the practical driving test. Her fourth test, which cost $60, was also failed because of a faulty vehicle light.
"My nerves failed me every time," she said. "I was confident at first, but I'm not now. I had a job when I started, but now I'm going to have a baby and I'm living on a benefit. If I sit my licence and fail it will be money down the drain."
St John Driving Academy instructor Peter Aben said the ability of Northland drivers had increased "ten-fold" since practical testing was tightened up.
"A lot of restricted drivers now drive a lot better than most full [licensed] drivers because their skill level is being lifted so high to pass that test."
Many passing the tests before the changes probably shouldn't have scraped through, Mr Aben said.
Overall, Northland drivers were more likely to fail because of nerves rather than incompetence.
"The test itself is difficult ... [but] they are a lot more lenient than they were when it first started a couple of years ago."
The NZTA has defended the system, saying nearly 60 per cent pass the restricted test on the first attempt, and overall the pass rate is more than 50 per cent.
The more challenging restricted test was introduced to improve the safety of young and novice drivers, NZTA said. Among other proposed changes is a five-year limit on holding a learner or restricted licence.
Drivers who do not progress within the time limit would need to resit their theory or practical test. NZTA and Northland instructors
