High-income earners would bear the brunt of congestion charging in Sydney's CBD if it was introduced, according to an analysis of driver behaviour.

The analysis by the Grattan Institute comes as the new chair of the Productivity Commission, Michael Brennan, this week threw his support behind congestion charging, whereby road users are charged higher rates to enter busy areas or travel at peak times of the day.

Critics have argued such charges could hit low-income earners the hardest.

Traffic in Sydney's CBD. Credit:James Alcock

However, the Grattan Institute's transport and cities program director, Marion Terrill, said people who drove into the CBD typically had higher incomes.