Efficient traveling is the key to saving dollars and reducing pollution, the scientists said.

Multiply the effects times the 32 million drivers AAA expects to hit the nation's roadways during the long holiday weekend the benefits add up.

First tip: "Most cars hit their fuel-efficiency sweet spot around 55 miles per hour, but fuel economy quickly declines at higher speeds," UCS said in a statement.

Second tip: Check your tires. Tires "naturally" lose pressure over time and "under inflated tires require more energy to move down the road."

Third tip: Get a tune-up. Replacing a dirty air filter can boost fuel efficiency 10 percent, about a 35 cent per gallon discount.

Fourth Tip: "Be weight conscious" the scientists said. "For every 100 pounds of extra weight … fuel efficiency decreases by 1 to 2 percent."

Fifth Tip: "Over the long haul, buy a high miles per gallon vehicle," the scientists said.