Additionally, renewable fuels such as corn-based ethanol have been blended with gasoline since 2008 and average about 10 percent of each gallon sold. Unlike butane, however, ethanol blends cost more to produce, so it leads to higher gas prices during the summer months when butane is reduced. The EPA has estimated the impact to be 2 to 4 cents per gallon.

Despite passage of a recent ban on such ethanol-blended fuels in Augusta, where lawmakers hinged the ban to similar measures having to be passed in at least two other New England states, the blends are still leading to higher out-of-pocket expenses as we travel more in the summer and crank up the A/C. Although winter heating bills are behind us, consumers should still be wary of how we use our fuel and make efforts to maximize our gas efficiency.

Here are a few tips to do just that:

Check your tires

Properly inflated tires can improve fuel efficiency by 3.3 percent, saving you 8-9 cents per gallon at the pump, according to the EPA. The agency also says fuel economy drops 0.3 percent for every one-pound drop in air pressure in all four tires, so at least in theory, having four severely underinflated tires could reduce gas mileage more than 3.3 percent.

To locate the correct inflation for your vehicle, don't look on the sidewall of the tire it could fit dozens of very different vehicles. The recommended pressure is most commonly listed on a sticker inside the driver's door. If there's no sticker on the door, you can usually find the specs in the owner's manual.

Remove excess weight

Get that junk out of your trunk! Avoid keeping unnecessary items in your vehicle, especially heavy ones. An extra 100 pounds in your vehicle could reduce your fuel efficiency by up to two percent. 

Plan ahead

Combining errands into one trip saves you time and money. Several short trips taken from a cold start can use twice as much fuel as a longer multipurpose trip covering the same distance when the engine is warm. Sketch a rough map of your path in most instances, taking a spiral pathway is much more efficient than one that looks like daisy petals.

Avoid idling

Even during the colder months of winter, idling to warm your car up is very wasteful. Cars warm up more quickly and efficiently when they're driven. If it's really cold say single digits or lower you can begin driving even after just 15 seconds of startup. Idling can use a quarter to a half gallon of fuel per hour, depending on engine size and air conditioner use. 

Leave early and drive more slowly

While each vehicle reaches its best fuel economy at a different speed, gas mileage decreases rapidly at speeds above 60 miles per hour. According to Fueleconomy.gov, each five miles per hour you drive over 60 mph is like paying an additional 24 cents per gallon.

Other tips to help improve gas mileage: 

• Don't ignore the check engine light, it may be trying to tell you something important that could save you money on gas.
• Washing and waxing your vehicle can make a surprising difference towards improved fuel economy because a clean car slips through the air more easily. Also, broken, cracked or missing underbody panels can seriously cut fuel economy.
• Your car's air filter is probably fine. Unless the air filter is more than 30,000 miles old, it's unlikely to be dirty enough to make any measurable difference in fuel economy.
• Roll up the windows and turn the A/C on. At speeds of 25 mph or more, aerodynamic losses due to open windows are typically greater than mileage that may be lost due to using the A/C.