NSW Opposition leader Luke Foley has vowed to reintroduce the cash-back system for Sydney's M4 motorway that would see $193 million returned to western Sydney motorists each year.

In an election pitch to western Sydney and to address cost of living concerns, Mr Foley told Labor's state conference on Saturday that some motorists now spend more on tolls than petrol.

His announcement received a standing ovation when he addressed 800 delegates in Town Hall.

Luke Foley says he will reinstate the toll cash-back scheme for the M4. Credit:Rob Homer

The state government reintroduced tolls on the M4 in August last year, a month after the widening of the road to four lanes in each direction was completed.