GoBankingRates.com says ARCO filling stations in California among those adding surcharges.
U.S. District Court Judge John Gleeson batters lawyers in hearing over what he said were misleading websites.
The pending anti-trust settlement, pitting the six major card issuers and two major card brands against the retailers, has sparked a legislative backlash.
Eleven states now ban retailer surcharges on credit card transactions.
Card, retail executives say practice unlikely to take root in U.S.
Twenty-eight states either have bans or are considering them in wake of proposed antitrust settlement.