There were blushes in NSW Labor on Tuesday, when leader Chris Minns’ “zero-emissions” campaign bus ran flat – forcing a return to an old-fashioned gas guzzler.

The much-hyped electric bus was on the road from Warragamba Dam in Sydney’s south-west on Tuesday morning with travelling media and Labor staffers on board.

But it reportedly ran out of charge on the way back to Camden for a street walk, prompting an urgent callout for a replacement coach.

Labor’s campaign was soon back on the road, with staffers telling News Corp passengers had been moved to a different bus “just to be safe” after an “issue with the charging”.

Mr Minns was particularly proud of the 12.5-metre Australian-made bus at the start of his run for office, particularly its “all-electric” status.

Tuesday’s fizzle gave Premier Dominic Perrottett a chance to have a swipe at his election opponent.

“It’s no surprise that Labor’s bus has broken down, just like their budget broke down yesterday,” he said.

It was just one of several attacks on economic credentials on Tuesday, as the race towards the NSW election finish line neared.

Mr Minns began his morning running with the party’s frontbenchers in the Liberal-held western Sydney seat of Oatley. Then he steered the electric campaign bus to the marginal Liberal seat of Wollondilly, where he attacked the Coalition for failing to fund its plan to raise the Warragamba Dam wall.

“There is no money allocated for this project, not a cent,” Mr Minns said from the dam’s viewing deck.

“The project that costs $3 billion to build.”

He warned more privatisation was on the cards if the Coalition was re-elected.

Last year, Mr Perrottet committed last year to raising the wall at Warragamba Dam, saying his government would fund the project without federal assistance if necessary.

It said the project could reduce the number of homes affected by major flooding from 15,000 to 5000.

Also on Tuesday, Labor also announced it would make further reforms to the rental market, tightening data retention rules for real estate agents, an review the role of the NSW Civil and Administrative Tribunal in rental disputes, as well as provide an additional $1 million for tenant advocacy services

Mr Perrottet, meanwhile, met firefighters in regional NSW. He began the day in the Southern Tablelands town of Taralga, meeting RFS volunteers as they prepared for a day of hazard reduction burning.

The area lost about 10,000 hectare in the devastating 2019-2020 summer bushfires.

With four days until polling day, Mr Perrottet is trying to shore up the must-win seat of Goulburn, which is held by Local Government Minister Wendy Tuckerman with a 3.1 per cent margin.

He visited the iconic Big Merino and announced $3.2 million to build a horseriding facility in the area for disabled residents.

Mr Perrottet also dropped in on local cafes, where he played barista for a few minutes before getting back to the campaign trail, listening to residents’ concerns about staffing issues.

The day after the Parliamentary Budget Office released its costings for the election policies made by the parties, both sides attacked each other’s economic credentials.

The Coalition is estimated to deliver a $100 million surplus over the next four years, while Labor would add $1.4 billion, according to the budget office.

Mr Perrottet said Labor had a “black hole” in its costings after the PBO questioned the party’s pledge to scrap the government’s 3 per cent wage cap for public sector workers at zero cost to the bottom line.

Mr Minns defended the policy on Tuesday, saying scrapping the cap on wages would put NSW back in line with the rest of the country.

“It’s necessary to sit down and negotiate with our essential workers. I’m talking teachers, police officers, firefighters, paramedics,” he said.

Budget savings and productivity gains would be found during negotiations, and economic guardrails would be in place as the party talked with unions, Mr Minns said.

“We need to do this because under the Coalition, under Mr Perrottet, he’s used the wages cap as a vice,” he said.

“His decision in July 2020 to reduce [wage] increases down to 0 per cent has had a devastating impact on essential services.”

Labor said it had calculated $3 billion in savings in its budget that would fund public sector wage increases.

Treasurer Matt Kean also attacked Labor’s policies, saying the PBO analysis revealed Labor would have to cut projects to pay for to negotiate new pay deals with workers.

“Their budget black hole is growing by the day,” he said.

The NSW election is on Saturday.

-with AAP