Melbourne taxi drivers will be given four times as many chances to pass a controversial knowledge test, after nearly 99 per cent of cabbies failed it.

The test was introduced in July 2014, and must be completed by all new drivers in metropolitan Melbourne, and those with less than five years' experience.

There had been complaints that the test was too hard, with just six out of 444 drivers passing since it was introduced.

The taxi 'knowledge test': Introduced July 1, 2014

Introduced July 1, 2014 444 people have sat the test

444 people have sat the test 6 people have passed all three modules

6 people have passed all three modules 54 people have passed one or more modules

54 people have passed one or more modules 17 existing drivers have failed a module twice, losing their endorsement

Instead of having two chances a year to pass the test on driver behaviour and geographical knowledge, drivers will now have eight.

Taxi Services Commissioner Graeme Samuel said the standards expected of taxi drivers remained high.

"The test itself hasn't changed, nor has the standard we're requiring of the drivers - those standards remain the same," Mr Samuel said.

"What we're doing though is giving the drivers four chances to sit the test and we're giving them some assistance in the training by producing a training manual."

Previously, drivers were allowed two attempts to pass each of the test's three modules.

Mr Samuel said the new training manual would be in addition to training hitherto provided by training schools, or the taxi companies themselves.

"We're finding that the training is not up to scratch, as a result the drivers are sitting for the test and failing so the Taxi Services Commission has decided to try to assist the drivers by providing its own training manual," he said.

The test includes three modules to establish general and geographical knowledge, as well as driver behaviour and aptitude for customer service.

Each module requires applicants to answer 55 questions in an hour.

They must also meet a "satisfactory degree" of understanding and proficiency in the English language.

Mr Samuel said that the changes were not an admission that the test was too difficult.

"The test remains the same, the test is exactly the same test that's always been in place," he said.

"What this is doing is saying to drivers that we'll give you greater opportunity to be able to sit for the test."