Economists warn that Peter Dutton’s pledge to halve the fuel excise is nothing more than a populist sugar hit that will disproportionately favour the wealthy and do little to address the problems plaguing the budget.

The opposition leader on Thursday promised to cut the price of petrol by 25¢ a litre for one year if he wins the federal election, as Labor and the Coalition compete for votes in a campaign squarely focused on the cost of living.