Every would-be cabbie in the state who has sat the tough new driver Knowledge test has flunked out since it was introduced in June.

The 100 per cent failure rate has left the industry pondering whether it will have enough drivers to work the hectic Christmas holiday period, given the test must be sat by all drivers with less than five years' experience, as well as industry newcomers.

Karen Downie, Drivers Services Manager at 13cabs. Credit:Eddie Jim

"It is very much a transient workforce, though you do have your core career driver group," Stuart Overell, chief operating officer of booking network 13Cabs, said. Government figures show 4250 out of 16,000 active drivers have less than five years' experience.

Karen Downie, an experienced driver trainer at 13Cabs, is the only person in Victoria who has passed the knowledge test, which she described as "very tricky".