Cheap gas to go

GPS units have turned into information powerhouses. Besides displaying maps and directions, these popular gadgets have become Swiss Army knives for travelers, offering directions to pizza parlors, hospitals, hotels, tourist attractions, and - for an extra fee - critical information ranging from local traffic conditions to the location of speed cameras.

Now, with gasoline topping $4 a gallon, add local fuel prices to the list of extras your GPS receiver can show you. Or so the makers of TomTom GPS devices assert.


The company's new gas price service - available on TomTom Go 720/920 and newer models - will not only display gas stations in your vicinity, but also tell you how much each station is ostensibly charging for fuel, with prices updated every four hours over the Internet or by compatible cell phone.

The good news: TomTom may be able to help you find the cheapest gas. And that may be worth the $15 annual fee for the the service, especially if you put on lots of miles in unfamiliar places.


The bad news: There are times when TomTom's service doesn't have a clue what the actual price of gasoline is. I'm not talking about missing by a few cents per gallon here and there, but by 15 to 20 cents a gallon. At other times it's accurate to within a penny or two. So don't count on consistency.

If you're not familiar with the acronym, GPS stands for Global Positioning System, an array of 24 government navigation satellites that circle the Earth, broadcasting signals that enable folks with GPS receivers to determine their position within 100 feet or less.

The new TomTom Go 930 I tested is a great high-end GPS unit, with enough bells and whistles to please the most gadget-happy traveler. I'll do a full review down the road, but TomTom is pitching the fuel price feature, so that's what I tried first.

I connected the TomTom to my computer's USB port and then subscribed to the fuel service online through the company's Web site.

Fuel prices for 100,000 stations nationwide are provided by OPIS (the Oil Price Information Service) and IRIX, best known an aggregator of real-time, premium traffic data that owners of compatible GPS units can display with an add-on FM receiver.

Downloading fuel prices takes only a minute or two over a broadband connection. On the road, you can also use a compatible GSM cell phone with Bluetooth capability (most of these are available on T-Mobile and AT&T; networks). My phone was not so blessed (you can look for your model on TomTom's Web site). So I couldn't test that feature.

TomTom says the data is updated every four hours, but that doesn't mean stations report prices that often. In fact, many don't report for days at a time. More about that later.

Armed with my first download, I stuck the TomTom on my windshield in the driveway of our home in Pikesville and asked it to find the cheapest fuel in the neighborhood. You can also ask for prices from all local stations and from stations on your route.


TomTom's winner was an Exxon station near Woodlawn, which wasn't exactly around the corner, but at $3.78 per gallon (about 25 cents less than my local stations were charging), it looked like it could be worth the trip.

The TomTom displayed a route to the station and guided me there flawlessly, but when I arrived, the price was $3.93 - a full 15 cents higher than TomTom's listing.

I looked up other stations in the neighborhood on the TomTom and saw prices ranging from $3.78 to $3.93 - but when I visited in person, the prices also were much higher.

The same thing happened wherever I drove over the next two days - including trips downtown, to Towson, and to Northeast Baltimore. On the third day, the prices in my neighborhood were updated to reflect something closer to reality.

Back on TomTom's Web site, I found that much of the gas price data comes from truck fleets, which means stations that don't get much truck traffic might not report very often, or at all. Nor are most independent stations even listed - and they're traditional sources of cheap gas.

According to the company, 60 percent of the stations report within 48 hours. Working backward, that means price information from 40 percent of the stations is even older.


In a business where prices can change by the hour, especially now, this is not what I would call data deluxe.

You'll find more accurate prices by logging on to the AAA Web site before you go to work - it lists the prices at many local stations, along with the time the most recent report was filed.

In the end, however, the exact price might not matter. That's because gas station operators are creatures of habit. Even though the TomTom initially displayed prices that were way too low, it was pretty accurate on relative prices - the cheapest stations on its local lists were still likely to be among the lowest in the area. This isn't surprising - competition is intensely local, and cheap stations tend to be consistently cheap.

Another thing I found was enough real-world price variance to make a short detour worthwhile. Whenever I stopped to check prices within a mile radius of various suburban locations, I typically found prices ranging from $3.93 to $4.08, a gap of up to 15 cents per gallon. On a 15-gallon fill-up, that's a difference of $2.25. So without straying too far from your path, you might be able to save a few dollars over time.

Bottom line: I wouldn't buy the TomTom 930 for the gas price feature, but if you buy one for other reasons (and there are plenty of good ones), go ahead and splurge on the fuel service. In areas where you're not familiar with the stations, it could pay for itself.


For more information, visit