ATLANTA -- When prices go up, we get worried. But what can we do about it? Over the years, different fuel savers have made promises to improve our mileage. “Back in the 70’s it was the hundred miles a gallon carburetor. They don’t make carburetors anymore,” said Mike Quincy with Consumer Reports.

The EPA has tested lots of additives and so has Consumer Reports.

“Consumer Reports will test all the things that you can add to the tank or do this to your engine to save fuel, we found that they don't do anything,” said Quincy.

Now, there’s a new product that says you will save on gas, but unlike most gadgets out there, you don’t stick it in your gas tank or your engine. You set it on your dash.

The Digital Fuel Mizer aims to change your behavior. Thing of it like a digital nag. Drive too fast, hit the brakes too hard and it’ll beep at you. But does it work?

LINK: DigitalFuelMizer.com

Channel 2’s Clark Howard decided to give the Fuel Mizer a really tough test: Joe Buehler. He's already been tracking his gas mileage for years. And he's careful about every drop of gas. His Civic is supposed to get 29 miles per gallon. Joe gets 32.

“I'm trying to save money by coasting, because I have a stick shift so I'm trying to coast more,” said Joe.

Joe’s Civic is supposed to get 29 miles per gallon, but with Joe driving, he gets an impressive 32 miles per gallon. Can he top that by using the Digital Fuel Mizer?

He agreed to try. A week later, we met him at the gas pump for the results.

First what did he think of the gadget? “It was a little bit annoying at first because it reminded me of the old radar detectors,” Joe said. “But once you get into the habit of driving with it, to let you know you’re going too fast too quickly or breaking too fast, I made it stop altogether because I was driving in such a way it wouldn’t go off anymore.”

Then he gassed up his Civic. The results? He got 36 miles per gallon using the Digital Fuel Mizer. That's an increase of 12 and a half percent.

Since Joe’s tank holds 12 gallons, that means Joe can drive 48 miles farther on a tank of gas using the Digital Fuel Mizer. Joe has decided, it’s worth the money and he doesn’t even care if his driving annoys other people on the road.

“Driving slow for me is no problem. People beep at me or try to pass me but I’m the one smiling because I’m saving money,” said Joe.

“Car and Driver Magazine said that this baby will save you about 10 percent of the cost of your fuel,” said Clark. “You’ll make the money back after several months. It’ll cost you $60 or so. But you really want to save money? When it comes time to replace your baby, buy a fuel efficient one. Americans are doing that now in huge numbers, saving themselves $1,000-$1,500 a year in fuel.”