Cheap gas fact check
Information on gas-tracking Web sites can't keep up with rapidly changing prices at the pump.
NEW YORK (CNN) -- The tank is near empty as we drive across the Brooklyn Bridge in search of a cheap fill-up outside of Manhattan. Approaching the brownstone-packed Park Slope neighborhood, I type the zip code "11217" on my laptop which is connected via aircard to automotive.com, one of at least a half-dozen sites that promise to locate the lowest-priced gas station wherever you may be driving in the country.
Automotive.com gets our first test because the firm promoted itself to CNN.
But, each time I type in the zip code the site responds, "data is not available."
"You may have caught one of the bubbles there when data was being updated and downloaded," automotive.com's James Bell later explains to me.
Fortunately, I've brought along a print-out from the site, only a half-hour old, which lists stations in the neighborhood. It says the Getty station at 538 Third Avenue is charging $4.19-a-gallon. But the price on the pump for regular is $4.29.
"When was the last time you were charging $4.19 here?" I ask station attendant Paul Pierre as he pumps gas.
"Oh, It was two weeks ago," responds Pierre.
Andrew Thomas, a mechanic, has just filled up with super, "because I get more mileage." He's paid $4.49, 10-cents higher than the quote on automotive.com. "Not accurate at all," says Thomas.
Back in the car and driving down Third Avenue, automotive.com now is providing live price quotes. Regular is $4.25 at the neighborhood Shell station, the site says. But the actual price is CHEAPER, $4.19-a-gallon.
That's the price automotive.com quotes for a nearby station at 169 Third Avenue, which the site says is a Mobil. But we arrive to discover there is no Mobil at 169 Third. It's a Citgo.
"I'm not Mobil," says manager Motasem Mohamed.
"Have you ever been Mobil?" I ask.
"No. Since we started here, Citgo, And it been Citgo always," answers Mohamed. "Been here more than 10 years, more than 10 years."
At least automotive.com's price quote for regular is correct, $4.19. But it has the wrong premium price, $4.32, ten-cents too low.
The Web site says its prices come from credit card transactions, but concedes its data provider - which it would not name - is not always timely.
"It may be four, five-to-seven days before a...gas station can upload us with the new information that then goes into that vendor and then is supplied to automotive.com, So there can be some gaps in the service there," said Bell. "We think it's the best and most reliable resource for this because it's based on hard transactional data."
Yet automotive.com was entirely accurate at only one of the five Brooklyn locations we checked, a Hess station where regular was selling for a relative bargain of $4.05-a-gallon, and premium was available for $4.29, prices that gasbuddy.com also pinpointed.
Gasbuddy.com, relies on volunteer spotters who are members of the site. Even if their reports are accurate, these days they can quickly be outdated, as we learned. Gasbuddy.com said a Park Slope Sunoco station was charging $4.05-a-gallon for regular. We arrive at 5 p.m. to find regular at $4.09.
"This morning, in the morning we were $4.05," says Khan Rana, the station attendant, explaining that he raised the price at 11 o'clock.
It was a similar story at the Mobil station on Hamilton Avenue: the $4.05 listed on gasbuddy.com was already history. Customers are paying $4.09 for regular.
"All day, all week. It was the cheapest one in the neighborhood," exclaims Sandra Escalante as she fills up one of her car service sedans. "It was $4.05 and now it's nine. It's not the cheapest one in the neighborhood."
"There's only so much we can do," concedes Jason Toews, co-founder of gasbuddy.com
"If a station changes their price and we don't have an update after that, then it may be an older price and no longer be the correct current price."
At least gasbuddy.com and automotive.com are more useful in this neighborhood than mapquest gas prices, which shows inexpensive stations in New Jersey when we plug in the Brooklyn zip code.
Fact is, with gas stations changing prices so frequently, sometimes several times-a-day, it's almost impossible for the cheap gas Web sites to keep up, even when they are getting reliable price reports. 
