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Thousands of people will hit the road this year on their way to the next great American road trip. And as the weather gets warmer, even more will be venturing out on those long stretches of highway.

A road trip often means big bucks will be laid out on travel costs. From pricey snacks to premium fuel to costly car washes, the route between your home and your destination is a virtual minefield of unnecessary purchases that can drain your pocketbook. Read on for advice on how to reduce summer travel costs.

1. Higher fuel consumption

It may feel more satisfying to fly around other drivers on the highway, but the joke is on you. Your gas mileage will decrease rapidly after your speedometer hits 60 mph, boosting your travel costs.

In addition, rapid acceleration and braking also can reduce your gas mileage. Driving at a lower speed can help you save as much as 33% on your cost to fill up at the pump, says Jody DeVere, the chief executive at AskPatty.com, an automotive advice and education website for women.

"Observing the speed limit is also safer, so you may save more than just money," DeVere says.

2. Expensive roadside dining

A little planning can save you from having to buy those pricey bags of chips at roadside gas stations.

Before you leave, visit your local grocery store and stock up on snacks and drinks, then toss them in a cooler that's small enough to stash in the back seat or trunk, says Stacey Hylen, a business coach in Montreal who spent seven years on the road while working in sales.

If your trip is long enough to require a restaurant meal, sit down for road food during the first half of the day to save money.

"Breakfast and lunch are always priced lower than dinner," says Karen Hoxmeier, a mom of three and founder of the bargains website MyBargainBuddy.com. "When you dine out, make dinner your lightest meal."

Also, look online for coupons for chain restaurants commonly found just off the highway. For example, the bar-and-grill chain Chili's frequently puts out money-saving printable offers on its website and via email.

3. Highway gas-station prices

Pulling into a gas station right off the interstate or turnpike saves time, but it can cost you money. Gas prices just off the highway may be higher than at stations at discount stores and near supermarket shopping centers, DeVere says.

Warehouse stores, such as Sam's Club and Costco, also offer cheaper gas, but you have to be a member. If you are, check your route beforehand to see if there are any locations on the way.

Finally, smartphone users can download free applications, such as GasBuddy, to find stations closer to town that offer fuel at lower prices.

4. Premium gasoline -- usually

The debate over regular gas versus high-octane fuel has raged for years. But the truth is simple: Few cars benefit from premium grades of gasoline.

"For most cars, the recommended gasoline is regular octane," DeVere says. Premium gas won't help your car perform better or increase your gas mileage, and it can cost you as much as 20 cents per gallon more than regular, according to the Federal Trade Commission.

A small number of cars do require high-octane gasoline, so check your owner's manual -- and even then, read carefully. "Find out if the higher-priced gas is required or just recommended," DeVere says. If it says "recommended," you're probably fine using regular gas. If it says "required," you should go for the higher grades.

5. Automatic car washes

Think hard before ponying up those extra few bucks for automatic car washes at gas stations. They may not get your car entirely clean and might even damage the exterior.

"Some older car washes use abrasive brushes instead of cloth ones, which can leave small scratches in a car's finish," DeVere says.

Often, a more cost-effective option is a self-service wash, which requires you to scrub the car but can be useful for removing heavy, caked-on dirt. Or skip the wash altogether while you're on the road and periodically spot clean the headlights, windshield and mirrors for safety purposes, says Eric Wulf, chief executive of the International Carwash Association in Chicago.

Finally, you may want to wash your car before you leave home. "A good wash with wax or sealant goes a long way toward protecting your vehicle from road salt and corrosion," Wulf says.

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