JACKSONVILLE, Fla. -- What gas customers see advertised may not be the price they pay at the pump.

It's because of something gas inspection experts call two-tier pricing.

In response to many questions from viewers about the different pricing, First Coast News asked why, if it's legal and what you can do about it.

Gas stations using two-tier pricing advertise one price for cash (or company-specific credit cards, such as Shell or Chevron), but display another price at the pump for credit cards.

"They just pull up to the pump to get their gas and then realize, 'Oh, they charged me more than what that sign said,'" explained Roberta Lawson, a supervisor for petroleum inspection in North Florida.

The practice is popular in South Florida but it's becoming more common on the First Coast, according to Lawson.

The reason stations do it may be because of steep vendor credit card fees.

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