The consumer watchdog is still seeking answers from Volkswagen on the impact of the recent scandal on Australian car buyers.
Australian Competition and Consumer Commission chairman Rod Sims told a business function in Brisbane on Tuesday he remained concerned about allegations that software installed in some Volkswagen, Audi and Skoda vehicles had been used to defeat emission testing regimes.
"We are still pressing VW Australia to understand the extent of consumer detriment," Mr Sims said.
Volkswagen has announced a voluntary recall of almost 100,000 cars, after it admitted to the existence of emissions-cheating software in its Australian diesel vehicles.
However, it released no details about what repairs might be taken, and told customers to take no action until a technical solution was provided by its German head office.
The Australian action came three weeks after the German auto giant confessed to installing "defeat devices" in more than 14 million cars worldwide and a week after head office announced plans to refit and recall the engines of five million vehicles worldwide.
Volkswagen Australia has been criticised for keeping the local market in the dark in that time, and referring all queries about the scam to the global head office.
Mr Sims said VW's alleged behaviour is a "clear example of the ACCC's general concerns with truth in advertising".
He said truth in advertising was a priority because many consumers valued cars with low emissions and they may well have bought another vehicle if they had known the facts.
Truthful advertising was also important to drive new research into low emission engines.
"The ACCC's enforcement investigation into potential breaches of mandatory standards and the Australian Consumer Law is well underway," Mr Sims said.
