That's what resourceful consumers have been learning in recent weeks as they visit--by the hundreds of thousands--gas price Web sites such as GasBuddy.com, GasPriceWatch.com and AAA's Fuel Price Finder tool, which can be found through the association's Gas Watcher's Guide.
According to that site, one San Francisco gas station recently sold regular gas for $3.20 per gallon, while another--just three minutes and eight tenths of a mile away--sold it for $2.80 per gallon. That's a 40-cent per gallon difference, or a $6 difference when filling a 15-gallon tank.
Traffic to Gas Watcher's Guide has jumped 54 percent in just the past week, a spokeswoman for AAA of Northern California said. Those users were likely finding their way to the Fuel Price Finder tool, which uses data from recent credit card transactions to calculate how much people have paid for gas.
Meanwhile, consumers also discovered GasBuddy.com and GasPriceWatch.com. Both are about 5-year-old sites that rely on data from motorist gas spotters, but they present the information in different ways.
GasBuddy.com co-founder Jason Toews, whose site is based outside Minneapolis/St. Paul, said his site is attracting an average of 700,000 to 800,000 different visitors a day, up from about 200,000 last month. "have driven people to the site," he said.
GasBuddy.com gets its information from 170 different gas price Web sites, all operated by GasBuddy. It recently conducted a survey that found the prices appear to be changing driving habits: The survey showed a 6 percent drop from last summer in the number of people driving 500 miles or more on a summer vacation, Toews said.
GasPriceWatch.com founder Brad Proctor said his site got about 1 million individual visitors in all of July, and then 1 million more in just the first five days of August. So far this month the site has had about 4.5 million visitors, or about 236,000 a day, he added.
Proctor, who appeared as a guest on "Good Morning America" on Monday, said his site rewards gas stations with the best prices and punishes those with the worst prices. More importantly, he added, it "shows the economic power" of the everyday consumer. He envisions a day in the near future when people routinely access his site from their cell phones before they purchase gas, he said.
Average U.S. gas prices by region on Friday, according to the AAA, were: Pacific Coast, $2.73; Mountain West, $2.49; Southwest, $2.55; Great Lakes, $2.69; Southeast, $2.57; Northeast, $2.58; and Mid-Atlantic, $2.59.