Professionals like Doug Privitt of Columbia, who has worked on cars for half his life, said, "Biggest thing [is], have it checked. Get it tuned up."
As for those increased mileage products, Privitt said, "Today's car, the computer really controls that so well. It depends on the car to a certain extent. Some of the older cars that have a problem, in some of them, it could help. But, if a car is working efficiently, the computer's doing its job, I don't really feel like it would help enough to justify the cost."
The Bioperformance company claims its pill increases gas mileage by 30%, although the attorneys general of Texas, Kentucky and Florida disagree. All three states have barred selling the product.
Energy spokesman Larry Archer of Missouri's Department of Natural Resources said, "We encourage people to adapt their practices, their behaviors, as opposed to investing in all sorts of the latest whatever they might be seeing on late-night television, advertised to improve this or improve that."
Privitt recommends adding a fuel injector cleaner in your gas tank, although not for every fill-up.
"Fuel injectors, they spray a very small pattern of fuel into the engine," he explained. "And, if they get dirty, then that spray goes all over the place."
Privett said the injector doesn't spray evenly, so your engine may not get enough at the point of combustion to fire effectively. He recommends adding fuel injector cleaner about every fifth fill-up.