Twenty-five Freedom Fuel Network stations opened across Pennsylvania and New Jersey, selling petrol at about 80 eurocents per litre—well below major US chains.
The company said it cut prices in response to President Donald Trump's call for cheaper fuel as pump prices have swung sharply since the Iran war began in late February.
Freedom Fuel said the pricing drove fuel volumes up more than 50%, with some sites reporting growth above 100%, and described the rollout as seeing "explosive growth."
Trump's public praise at the launch fueled speculation about White House involvement, but a spokesperson told CBS News the chain is privately owned, with no federal stake or subsidy.
The debut lands amid a broader oil-market shock tied to the Iran conflict, which has pushed US and European fuel prices sharply higher and then lower with shifts in fighting.