Only one taxi driver has passed Victoria's knowledge test designed to "weed out" bad drivers, prompting concerns that Melbourne could be hit with a cab shortage.
The test, which was a key recommendation in last year's taxi industry inquiry, was introduced in June by the Napthine Government in a bid to lift industry standards.
It covers driver behaviour, customer service and geography.
Would-be drivers have two chances to pass the test before being forced to wait 12 months before taking it again.
Of the 234 people to sit the exam, driver trainer Karen Downie was the only person to pass.
"There's 55 questions in each unit and you get an hour to do it ... a lot of knowing your bus lanes and tram rules and how to deal with people with disabilities," she said.
"Having done the test now myself, I'll be much better at helping others to prepare for it."
The taxi services commissioner, Graeme Samuel, who previously described the test as a way of weeding out bad drivers, said he was not entirely surprised by the poor test results.
"What it indicates is that there has been poor training and poor assesment in the past," he said.
"You don't want drivers on the road who only understand one half of the behavioural skills that are neccessary to be able to deal with passengers."Industry warns of looming driver shortage in Melbourne
13Cabs' chief operating officer, Stuart Overell, has supported the test, but said it could lead to a shortage of drivers in coming months.
"If things don't change we're probably looking at a 25 per cent reduction in the taxi fleet by Christmas," he said.
"Taxi passengers will have to find alternative methods to get home as taxis will increasingly be booked out of Friday and Saturday nights."
But Mr Samuel said those claims were nonsense as concessions were being made for drivers who failed the test over the next six months.
"Drivers who fail this test are still being re-accredited to 2015," he said.
"Drivers, however, who come up for accreditation from the first of January next year and fail the test will have their accreditations removed.
"Frankly 13Cabs is just being mischievous putting out that sort of nonsense."