The Durbin amendment to Dodd-Frank legislation has seen interchange rates slashed by about 70% for debit card payments for fuel, says the EPC, which is a coalition of banks, credit unions and card networks opposed to the rules.

With high gas prices likely to play a major role in this year's presidential elections, the EPC has commissioned research from Phoenix Marketing International on the prevalence of debit card use at the pump.

A poll of 5166 consumers shows that 36% of all payments for fuel are made with a debit card - half of all non-cash transactions. The debit card share of both transactions and dollars is higher than any other payment method.

With US Energy Information Administration figures showing that nearly 134 billion gallons of gas were sold in 2011, this means that approximately 48 billion gallons were purchased using debit, claims the EPC.

Yet, despite the $1 billion a year this gives merchants "there continues to be no evidence that retailers are passing along savings," according to the EPC.

Trish Wexler, spokeswoman, EPC, says: "Whenever Congress meddles in an industry debate over who pays what, consumers never win. One side gets a leg up and keeps their windfall, while consumers end up footing the bill. No one is surprised to see that gas retailers are keeping billions of dollars for themselves, while their customers continue to be punished at the pump. Americans should go to their gas stations and demand what's theirs - a discount for debit."

Predictably, NACS, The Association for Convenience and Fuel Retailing, has dismissed the EPC claims. Jeff Lenard, vice president, industry advocacy, told CSNews Online "this 'research' shows the banks' absolute ignorance of the fuels market".