Here's how to keep more cash in your pocket when you're at the pump. Thinkstock By Stacy Rapacon, Online Editor Updated January 2015 Gas prices are down, and you can fill up for even less. Here are five ways to save on gas:See Also: Ditch Your Car, Save a Fortune 1. Search online for the lowest gas prices. Before you hit the road, head to the information superhighway. GasBuddy.com and its 12 million registered users will help you find the lowest gas prices in your area. Search the site by zip code or city and state to reveal the lowest local gas prices posted by other users. Better yet, download the GasBuddy app to find the best prices on the go. Keep in mind that prices may change during the day and nobody is fact-checking user-reported prices. So, the price you found online may differ from what you find at the station. You'll also want to check that the price on the pump matches what is on the sign. 2. Target the best day and time to buy gas. Don't wait until your gas gauge drops near the "E" to fill up. Better to note when you have a quarter-full tank and give yourself some time to locate and get to the station with the lowest price. Advertisement Planning ahead can also help you schedule some savings. The best time of day to refuel is before dawn or late at night; stations usually raise prices during the day, especially for rush hour. The best day of the week to score cheap gas varies, but the majority of motorists will find the best deals late in the week or over the weekend, according to a recent study from GasBuddy. (Some outliers: Gas tends to be cheaper on Mondays in Indiana, Iowa and Kentucky.) See the full analysis for the best day to buy gas in your state. 3. Improve your gas mileage with better driving habits. High speeds, quick starts and squealing stops burn more gas—and money. Smoother rides, with less pedal pushing, can improve fuel economy by up to 37%, according to Edmunds.com. Consider using your cruise control more often to keep your speed in check. And practice looking farther down the road to anticipate traffic. Light turning red? Ease off the gas well ahead of your stop. Idle cars are the devil's Big Gulp. According to the Energy Department's www.fueleconomy.gov site, idling can drain your tank by a quarter- to a half-gallon of fuel per hour, depending on the size of your engine and use of air conditioning. On the other hand, restarting your car will only sip up a few seconds' worth of gas, so you're better off powering down when you're parked or sitting in excessive traffic. Also, consider a GPS: It'll provide the fastest, most efficient route to your destination, which can save you money. And why drive if you don't have to? If you can't commute by bike or foot, try public transportation or find a carpool. Check if your employer offers subsidies for train or bus fares. And ridesharing services, such as eRideShare.com, Boontrek.com and Carmacarpool.com, make it easy to connect with others heading your way. (See Ditch Your Car, Save a Fortune for more on going carless.) Advertisement 4. Keep your car healthy. Proper maintenance of air filters, spark plugs and fluid levels is best for your car and wallet. The right tire pressure is also very important for good fuel economy. Every pound-per-square-inch under the manufacturer's recommendation for all four tires lowers your gas mileage by 0.3%. You also want to keep your car on the right diet. If it's not recommended in your owner's manual, don't waste your money on premium gas, which can cost 15 to 20 cents per gallon more than regular. And try to keep the pounds off your car. Large loads affect cars just as they do to mules or horses: They weigh the vehicle down and make it harder to speed up. In fact, your fuel economy may be reduced by up to 2% per 100 packed-on pounds. Smaller cars are especially put upon by excess cargo. 5. Make good on gas rewards. Carrying the right credit card can earn you rebates on gas purchases. Some cards will get you 5% cash back when you purchase gas. (See our picks for Best Gas Rewards Cards.) Shopping at certain stores can get you gas discounts, too. For example, you can save 10 cents per gallon for every 100 points you earn at Giant grocery stores.