Credit cards at the pump may not be best for budgets.

A new report suggests consumers who choose credit cards at the pump can help their monthly budgeting by choosing paper over plastic.

The report cites a growing number of gas stations that offer a lower, more prominently advertised price for consumers using cash over credit cards.

Gas station owners said the higher charge covers a fee that credit card companies charge merchants for credit purchases, The New Bedford Times reports. At times gas prices may differs as much as 10 cents per gallon of gas.

“I don’t think they should do that,” Guilmar Silva, a concerned Massachusetts resident told the Times. “They already make enough money off of us.”

Under current law, it’s not illegal to make distinctions between customers on the basis of payment method. However the condition of sale must legally appear in writing, the news source reports.

New reform from The Credit CARD Act stipulated that transaction fees must now be handled by banks, as a way to reduce charges to merchants on credit card purchases. However, there has been no word as to whether this savings will be passed on to budgeting consumers at large, or at the pump.