Motorists living in some parts of Sydney could be charged different rates to use the city's motorways, under options being considered by the state government.

But it has categorically ruled out two alternatives being considered by its predecessor — a congestion tax on motorists driving through the CBD, and putting tolls on untolled roads to create a continuous motorway network.

After commissioning former Australian Competition and Consumer Commission (ACCC) boss Allan Fels in April to take a fresh look at how to make Sydney's tolling system simpler and fairer, the government has now released a snapshot of the work the Perrottet government had done on the issue.

It reveals that motorists in the Western Sydney suburb of Horsley Park pay the most in tolls — racking up an average of $1,917 a year on their e-tags.

Residents in Silverwater ($1,596) and Kemps Creek ($1,343) are also among the biggest spenders.

Roads Minister John Graham said the test would be whether a new system could be fairer to those drivers who are most dependent on cars for transport.

"If this delivers a better deal for drivers who don't have other options in the outer suburbs of Sydney, then that's what we're looking for," Mr Graham said. 

Professor Fells said he would be focusing on looking at ways to bring the city's toll roads onto a single pricing model. 

"Each toll was negotiated and determined separately without consideration to it being a system, so there is scope to bring in one system of pricing across the 13 toll roads."

Mr Graham said that could include a structure where all motorists pay an access charge and a distance-based toll, but different areas would be zoned so cheaper rates applied to some parts of Sydney.

"Different charges for different areas, that should reward ... commuters travelling regularly long distances who don't have the options of public transport," he said.

Professor Fels will also consider time-of-day pricing with lower off-peak charges, including pricing discounts to encourage heavy vehicles to move freight outside the peak.

NSW Treasurer Daniel Mookhey said the government would still go ahead in January 2024 with the $60 weekly toll cap it promised at the state election.

He said Labor was committed to keeping the toll cap in place for two years while Professor Fels completes his report and the government considers its recommendations.

The cap will initially be on top of the $250 cashback scheme the previous government announced, but that scheme expires in July next year.

Mr Mookhey said the government was not committed to continuing the cashback scheme beyond that point.

"We were also up-front about the fact that with the previous governments toll relief when it expires, its expires. That's why we're committed to this program of reform," the treasurer said.