Auto advances make gas advice moot

Some tips on saving money on gas really are running on empty

» Customer fears and fuel costs hurt air tours

As gas prices continue the steady climb through $4 territory, getting the most out of a full tank has become more important than ever.

At the pump A look at prices per gallon for regular, self-serve unleaded in Hawaii and across the country over the last year. National average Yesterday: $4.072 Last month: $3.952 Last year: $2.971 Hawaii average Yesterday: $4.432 Last month: $4.099 Last year: $3.413 Honolulu average Yesterday: $4.327 Last month: $3.967 Last year: $3.308 Source: AAA Fuel Gauge Report

But what's fact and what's fiction when it comes to the best use of your $4.43 gallon of gasoline?

Most drivers probably know the standard tips for conserving gas -- drive the speed limit, keep tires properly inflated and remove excess weight from the car.

All good, says Elaine Beno, spokeswoman for AAA Hawaii.

But there probably are just as many myths as truths floating around when it comes to trying to get every last mile out of your fuel tank.

Tricks your parents may have told you on how to conserve gas -- use the windows instead of the air conditioning or turning the engine off instead of idling -- simply don't apply anymore.

While tips such as those may have once held true, newer technology and newer methods of measuring factors that affect fuel efficiency have made them as arcane as the carburetor, says Don Anglin, a retired auto mechanic and author of several textbooks on the subject.

"Some of the (ideas) faded away," he said.

Perhaps one of the most common debates is windows versus air conditioning. Conventional wisdom is that using air conditioning burns gasoline faster, so it's better to use the windows to keep cool.

"As time evolved and we had better and more accurate instrumentation, we found out that that wasn't completely true," said Anglin. "The other part of that equation was that the additional wind resistance caused by the windows being down often equaled the amount of fuel consumed by the air conditioner."

There is, however, some truth to the theory.

"Where the motorist might see the air conditioning difference is turning the air off in stop-and-go traffic," said AAA's Beno. "Having the air on in stop-and-go traffic, you're going to be using a little more gasoline."

One trick AAA does not advocate is turning the engine off in stop-and-go traffic, mostly because of safety concerns.

"The driving environment today has become more complex," Beno said. "Paying attention to yourself and other vehicles around you and what's going on in the driving environment around you is more important than trying to save a little bit of gasoline."

Like air conditioner systems, engines are more advanced today, and there is negligible savings, if any, to shutting an engine off and restarting compared to idling, said Anglin.

Another myth dispelled by AAA is the notion that fuel additives purchased online or through direct mail can improve mileage.

"We've tested all of them and they don't work," Beno said. "There's a lot of appeals on the Internet about increasing your gas mileage by buying 'X' product, and they just don't work."

Using a higher octane if your car only requires regular unleaded won't get you farther, either.

"What you really need to do is use the grade of gasoline that your car was made to use," said Beno. "If your owner's manual says you should use regular unleaded, you should use regular unleaded."

Other theories that suggest your car gets better gas mileage with a clean air filter all speak to having a well-maintained car.

"Just having everything really working well -- from your air filter to having your tires properly inflated to being on top of your maintenance -- is going to be the best thing for the vehicle and one of the best things you can do to get the most mileage you can," Beno said.