Published: Mar 05, 2011 2:40 AM EST
Updated: Mar 04, 2011 11:40 PM EST

LEE COUNTY, Fla. - One price on the sign and another price at the pump? You might want to pay close attention next time you fill up your tank.

Recently, we've gotten calls and e-mails from people wanting to know why the numbers they see on the side of the road doesn't always match up with what they pay. Katie Carsi of Cape Coral got an unpleasant surprise when she went to fill up at a Fort Myers Marathon station.
"The sign from the street when I drove by the station said $3.56 and then I went to go pump the gas and I put my credit card in, and I'm standing there waiting to get the approval, and I noticed the little box below said $3.68," Carsi said.

She went inside and asked the attendant, who explained it was only $3.56 per gallon with the purchase of a car wash. "I didn't see where it said "with purchase of car wash" for that amount," Carsi said. "I thought that was a very deceitful practice. I said I won't be buying gas here, and I walked out. I was very angry."

Sure enough, that  phrase was displayed below the prices. It's not uncommon, and it is legal. The Shell station at Corkscrew Road and I-75 does the same, but as makes it very clear with several signs surrounding the prices.

Some stations may also advertise one price if you pay with cash, but charge more if you pay with a credit card. Others will draw drivers in with low price, but as you can see, it's only after a rebate.

As gas prices continue to climb, you don't want to spend more than you have to. So next time you fill up, keep your eyes wide open.

"12 cents is just 12 cents per gallon, figure it out, that's only $2, but right now, as much as we are paying for gas, I don't think anyone wants to pay $2 more if they don't have to," Carsi said.

Marathon Corporation tells us advertising methods are up to individual owners and operators, and some stations choose to do that as a way of advertising their car washes. Prices aside, we have some tips from AAA on how to be efficient and get the most out of your fuel.

Pay for gas with cash if in an area where retailers offer a cash vs. credit price:                                                                     Many gas retailers now offer consumers a cash price that's 5 to 10 cents less a gallon than if they paid with a credit card. Retailers have to pay a transaction fee to credit card companies whenever plastic is swiped. By paying in cash, consumers save retailers money, and in turn retailers pass the savings on to motorists.

Drive sensibly and safely:
Aggressive driving, speeding, and rapid acceleration waste gas and can lower gas mileage by 33 percent at highway speeds and by 5 percent in city limits. Sensible driving not only saves gas, but is safer for yourself and those around you.

Remove excess weight:
Remove unnecessary items in your vehicle, especially heavy ones. An extra 100 pounds in a vehicle can reduce your MPG up to 2 percent. The reduction is based on the percentage of extra weight relative to the vehicle's weight and affects smaller vehicles more than larger ones.

Avoid constant braking:
Minimize the need to brake by anticipating traffic conditions. Be alert for slowdowns and red lights ahead of you, and decelerate by coasting whenever possible.

Use the air conditioner conservatively:
Most air conditioners have an "economy" or "recirculation" setting that reduces the amount of hot air outside that must be chilled. Both settings can reduce the air-conditioning load and save gas.