Free rego fairer than toll refund: premier

Labor says that if elected, it will extend the M5 Southwest toll cashback to the M4 Western Motorway in a policy that will cost $113 million in its first year.

Tolls were reinstated on the motorway between Parramatta and Homebush in mid-2017 after the road was widened to eight lanes as part of the WestConnex project.

But Ms Berejiklian said it was fairer to give all motorists savings regardless of which road they used, pointing to her policy to give free or discounted rego to regular toll road users.

Asked how it was fair to run a refund scheme for only the M5, the premier said the cashback was an "existing arrangement".

"We think that's fairer, we're not going to decide which motorists have savings and which shouldn't," she told reporters on Sunday.

"People who use the M5 can choose whether they want free rego, they can work out what works best for them."

The premier said her government was instead upgrading roads and building WestConnex which would cut travel times for people living in western Sydney.

Labor had predicted refunding M4 tolls would cost $200 million a year.

But Opposition Leader Michael Daley said the price was now down to $113 million in the first year, according to analysis from the parliamentary budget office.

Mr Daley sidestepped a question about the policy being just about a quest to win back the seat of Penrith, which is currently held by NSW minister Stuart Ayres.

"It's about making sure families in western Sydney who are struggling with the cost of living have a clear policy choice," the Labor leader said.

"If they want to pay for 46 years to use the M4, vote for the state government (and) if they want to travel for free, vote for Daley Labor."

The M5 cashback is only open to NSW residents who have registered for the scheme, have a toll account and a vehicle registered in NSW for private, pensioner or charitable use.

Australian Associated Press