14 Ways to Fill Up for Less at the Gas Station

Most drivers have heard they can get a little more mileage out of their gas tank by accelerating more slowly, coasting when they can, or laying off the air conditioning. But you don't have to change your driving habits or swelter in a hot car to maximize your dollar at the pump. Here are 14 ways to pay less for gas as you hit the road this summer.

Most large grocery chains help customers save on gas by linking savings to a loyalty card. Kroger's gas savings program gives shoppers 10 cents off each gallon at its gas stations for every $100 spent on groceries. Safeway offers a similar program through Sunoco gas stations.

Once you've found a good grocery-store gas-savings program, ask about special promotions. The Kroger deal includes double fuel points on gift card purchases, or 20 cents a gallon for every $100. The store sometimes even offers quadruple points on gift cards -- yes, 40 cents a gallon for every $100 spent.

If you're loyal to a particular company, don't leave money on the table by bypassing its rewards program. BP Driver Rewards members earn 10 cents off each gallon for every $100 spent on fuel. Shell offers discounts of 10 cents a gallon for every $50 spent on dining and 5 cents a gallon for other qualifying purchases, including travel.

You won't get huge savings buying discount gas-station gift cards, but it's still worth checking the most popular card resale sites. A recent search showed up to 7 percent savings on cards for major gas stations at Gift Card Granny, which aggregates the offerings on reputable resale sites such as Cardpool and CardCash.

You aren't crazy: Gas at the station on the corner actually was a lot cheaper the other day. Prices fluctuate throughout the week. GasBuddy crunched the numbers using three years of price data and found that Mondays usually average the lowest. Sunday is the next-best day to fill up.

Some people say filling up early in the morning, when it's cool, saves money because gas expands when it's heated. But Consumer Reports concluded that any savings wouldn't be worth the change in schedule. Stations may be more likely to raise prices in rush-hour traffic, though.

There's no guarantee Costco's gas will be cheapest, but if you're a member, it's worth checking. The Christian Science Monitor found that prices there run roughly 6 to 12 cents below competing stations'. But consider whether joining is worth it only for the gas. You'd probably have to fill up more than once a week for a year to recoup Costco's $55 membership fee.

Smartphones make comparison shopping easy. GasBuddy is among the most popular apps for finding the lowest gas prices wherever you may be. CNN Money also recommends Gas Guru and traffic-spotter app Waze, which can flag cheap gas.

If you aren't using an app to check prices, experts offer this rule of thumb: Bypass stations immediately off the highway, which charge for convenience, and think twice about filling up in affluent areas where customers aren't as price-sensitive.

Chances are you'll be swiping plastic for your next fill-up, so choose the card wisely. Certain credit cards offer up to 5 percent cash back on purchases including gas, although rewards categories may rotate throughout the year.

Some gas stations offer a discount to customers who pay with cash. Why? They avoid the swipe fees charged by major credit-card companies and fatten their bottom line.

Some websites let you take surveys, watch videos, or shop with retail partners in exchange for points that can be used to earn gift cards. One of the most popular survey sites, Swagbucks, includes Exxon, Chevron, ARCO, and Sunoco gift cards as rewards options.

You may think you're babying your car by buying the "good stuff," but premium gas offers little benefit for modern engines, according to Edmunds. Stick to premium if you drive a luxury car that requires it; otherwise, enjoy the savings of buying regular unleaded.

The biggest money saver may be simply remembering to hunt for deals. According to GasBuddy, when gas prices are low, there's actually more of a spread -- not less -- between the highest and lowest prices at the pump. Because of that, drivers who assume prices are low everywhere run a greater risk of overspending.