The Tune-Up Test: Can The $250 Maintenance Really Help Your Gas Mileage?

When you're spending 70 dollars or more a week on fueling up,  a visit to the gas station is quite a blow to the wallet.

"Gas is just too expensive right now," says Patti Roberson who has been looking for a way to cut down costs.

She helped us test out the Digital Fuel Mizer and the Fuelshark, two products that claim to improve gas mileage.  The Fuel Mizer claims to change driving habits, the Fuelshark says it make the electrical system more efficient.  She only saw minimal results with the Shark.

She says one this is for sure, with these prices it's hard to keep up with tune-ups.  And Patti admits, she doesn't think her 2008 Kia has ever had one.

"I bought it back in May of 2010 and I have not had the tune-up done on it yet," said Roberson.

Until now.

Mechanics Harry and Todd Brady, at Brady's Frame and Alignment in Spartanburg set out to make her Kia run at top shape.  

First up: The diganosis. 

A digital sensor shows a problem that could affect her gas mileage. 

"The car has a random misfire," said Todd Brady.

The mechanics say it's not firing properly on each cylinder.

Brady says fixing the problem "could actually save her fuel."

In addition to changing the spark plugs and checking the car for problems, your average tune-up includes replacing clogged air filters.

"That helps let that engine run just a shade without a pull on it," said Harry Brady.

It also includes getting the right amount of air in your tires.

"We need to keep your air pressure up in your tires, makes it roll easier," said Brady.

So the Brady's get to work.  And Patti keeps her fingers crossed.    

The results of a tune-up can vary.  In Patti's case they found a problem so it could really help her gas mileage.  But mechanics are quick to point out, for newer cars, it can only do so much.

"You can do more to an older car as far as tune-ups than you can to a new car because most of all the new cars are computerized set, that it tells the vehicle how much gas it needs to there's not a lot you can do to the later model vehicles," said Brady.

The whole process costs on average $250.  It's no small change, but Brady says even if it doesn't improve the gas mileage, regular maintenance can lengthen the life of your car.

Several hours later, Roberson returns to find out just what was wrong with the car.

"Your main issue was the injector was disconnected," Brady told Roberson.

Todd Brady predicts the fix could save her 2-3 miles per gallon.

RESULTS:

Now comes the drive test.  For 2 weeks Patti tracks her gas mileage to compare it with her average before the tune-up, 22.1 miles per gallon.

On the first fill-up Patti sees a slight improvement of two tenths of a gallon to 22.3

"The tune-up did help some, I am getting a little bit better gas mileage, but not a whole lot."

A week later her mileage is up to 22.7 miles per gallon.

Though it's not the 2 to 3 mile a gallon improvement predicted, Patti is pleased that her car is running more efficiently. Still she says she's learned something when it comes to her many attempts to reduce her fuel mileage: There is no quick fix.

"I need to just change my driving habits and I think that would be the best thing."