Australia's car owners are paying $1 billion a year more than they need to because car makers are refusing to share technical information with independent mechanics, according to the competition watchdog.

Key points: The ACCC says the lack of data sharing with independent mechanics could be costing up to $1 billion a year

The ACCC says the lack of data sharing with independent mechanics could be costing up to $1 billion a year Car manufacturers say they are reluctant to share information for safety reasons

Car manufacturers say they are reluctant to share information for safety reasons The Federal government agreed to improve information sharing in 2018 but little progress has been made

The chair of the Australian Competition and Consumer Commission (ACCC) told a parliament inquiry on Wednesday the voluntary data-sharing system that car makers agreed to in 2014 is not working.

"We are convinced that some form of mandatory arrangement needs to be in place," Rod Sims told the House of Representatives' Standing Committee on Economics.

"The sooner it's done, you're going to make life better for the independent repairers, which in turn makes life better for consumers trying to get their cars repaired at the cheapest price."

Problem getting 'progressively worse'

The Federal Government agreed in May last year that reform of the sector was a priority, but since then independent mechanics have complained that progress is too slow.

"We're for it as soon as possible," the Australian Automotive Aftermarkets Association's (AAAA) Guy Nicholls told 7.30 last November.

ACCC Chairman, Rod Sims, says cars are getting more complex but the problem is getting worse. ( ABC News: Andrew Kennedy )

"In Europe and in America, these schemes are already in place."

Shadow Assistant Treasurer Andrew Leigh quoted from a US Auto Care Association report that estimated data sharing in that country saved consumers US$26 billion a year.

He then asked Mr Sims if that figure suggested the cost to Australian consumers was over $1 billion a year.

"I can't fault the arithmetic on that," Mr Sims replied.

According to the AAAA, a standard service on a Camry costs about 25-30 per cent more at a dealership than at an independent mechanic.

It said the same Camry owner would save around $600 on a new set of tyres and new windscreen at an independent mechanic — if the car manufacturers shared the data for recalibration.

In 2014, car makers agreed to a voluntary scheme in which they would share more information, including computer codes, with independent auto repairers.

But Australia's consumer watchdog later found that was not working.

In a December 2017 report, the ACCC found the reluctance of car makers to share technical information was unfair, and had the potential to push up the costs of repairs and servicing.

"The cars are getting more and more complicated, so the problem's getting progressively worse," Mr Sims told the committee on Wednesday.

Lack of data frustrating

Matt Sontrop, an independent mechanic from Queensland's Bribie Island, said the lack of data sharing made his job more difficult.

"Ten years ago it would take you five minutes to turn out a service light. Now it could take an hour-and-a-half, two hours, three hours," he said.

Independent mechanics, like Island Auto Repairs on Bribie Island, find the lack of sharing information very frustrating. ( ABC News: Peter McCutcheon )

Car makers have been arguing the problem is exaggerated, and they have good reason for holding back some information.

"We cannot have a situation where people are tinkering with cars that are complex, because it puts the safety of motorists and other road users at risk," head of the Federal Chamber of Automotive Industries (FCAI), Tony Weber, told 7.30.

Mr Sims accepted there were some complex issues that needed to be worked through.

"That complexity is, when do you define information that they don't have to share under a safety heading versus when they should," he said.

"I understand people are giving further thought to that.

"Would we like it moving along faster? Yes, of course we would."