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.
mike.himowitz@baltsun.com
For more information, visit www.tomtom.com.
