Does It Work? 7 On Your Side Tests Out the Fuelshark

 As someone who commutes nearly 60 miles round trip every day Patti Roberson is on a journey to find anything that can increase her fuel mileage.

"I was wanting to see if there is something out there to help, you know, on gas, because gas prices are going up so much and it looks like they're just going to keep going up," said Roberson.

Last week she helped us test out the Digital Fuel Mizer which alerts drivers to gas guzzling habits through lights and sound.  But in Patti's case, it didn't work.  Her mileage actually went down.

So the question is, will the Fuelshark be any different?

The TV ad says "just plug it into your cars lighter or power adapter, the blue light tells you it's working and saving money."   And the makers of the Fuelshark say it makes your electrical system more efficient.  It's a concept some mechanics say can work."

"What they're trying to tell you is that they're boosting the power of the electronic system," said Mechanic Harry Brady with Brady's Frame & Alignment.  Brady said "It would make the fuel burn a lot cleaner if it would work."  

Patti fills up, sticks in the Fuelshark, sets her trip odometer to zero, and she's off for a week of driving.

"The Fuelshark saves me 3 to 4 miles per gallon."

The makers of the Fuelshark tell 7 On Your Side it has been shown to improve gas mileage by an average of 10%.

Patti's average mileage from 3 previous re-fuelings is 22.1 miles.   So if that holds true for Patti, her new mileage would be 24.3

Fast forward one week and we're back at the gas station with Patti for the big reveal.

After doing the calculations the Fuelshark is .7 miles per gallon better than her average.

"I was hoping for more but I was surprised that it improved it at all because I didn't really think it would," said Roberson.

True, her mileage only went up 3%, but it's a marked improvement over the results of the Digital Fuel Mizer where her gas mileage went down to 21.3.

And Roberson insists, she did more gas guzzling driving with the Fuelshark than with the Fuel Mizer.

"I did more around town driving, around Spartanburg and Greenville than on the interstates," she said.

The makers of the Fuelshark aren't surprised:

Clay Renshaw from Direct Brands says "We have sold thousands of Fuelsharks in the U.S. and tens of thousands of consumers overseas have used it successfully.  Only 3 customers have sent it back for a refund."

But Renshaw admits "It appears that older cars (2007 and before) seem to gain more savings than newer cars... probably due to the newer electronics in the newer models.

That may explain why Patti's 2008 Kia only saw a slight improvement. 

"If it improves the car's performance at all, nowadays it would help a lot."

But Patti says with today's gas prices, she'll take it.

HOW MUCH WILL IT COST YOU?

News Channel 7 calculated the cost of gas mileage from Spartanburg, SC, to popular vacation destinations for Upstate residents, using the gas price ($3.702 per gallon, click here to get the latest price) as of  May 2, 2011 and the national average gas mileage for a car (19.8 miles per gallon according to the US Department of Transportation as of 2005).

Here are the results:

Disney World-573 miles-$100.40 one way, $200.80 round trip

Myrtle Beach-237 miles-$44.31 one way, $88.62 round trip

Charleston-203 miles, $37.95 one way, $75.90 round trip

Washington, D.C.-469 miles, $87.69 one way, $175.38 round trip.

Calculate your gas costs here.

It may be cheaper to fly to your destination. Find out here.

GAS SAVING MYTHS

With gasoline prices hitting record levels, it seems everyone has a tip on how to save fuel. Much of the advice is well-intentioned, but in the end, much of it won't lower your gas bill. Find out more here and here.

Click here to get tips from the FTC on how to save gas.

HOW WE DID IT

Our test driver, Patti Roberson tracked her gas mileage for 3 weeks prior to testing.  To do that she set her trip odometer to zero every time she filled up.  Then on her next fill-up we divided her trip mileage by the number of gallons of the fill-up.  We averaged those 3 readings to get her average gas mileage before testing which was 22.1. 

Then Patti installed the Digital Fuel Mizer, filled up and set her trip odometer to zero once again.  After a week of driving she returned and her new gas mileage was 21.36.  Her mileage had gone down, so the Fuel Mizer did not work in changing her driving habits.

Next Patti installed the Fuelshark and repeated the process.  Her new fuel mileage was 22.8, a 3% improvement over her average mileage.