So, in The Early Show's ConsumerWatch, correspondent Susan Koeppen offers a warning for car shoppers.
While you might be worried about gas prices, you should also be concerned about the gas mileage figures you see on the window sticker.
Koeppen found out that many cars that seem to be gas sippers could really be gas hogs.
Retired firefighter Tom Mannino wanted an SUV, but didn't want a gas guzzler. That's why he bought a Honda Element. Its sticker said 21 miles per gallon in the city.
But that, he says, is not so.
"I'm getting 14. Between 14 and 15 miles to the gallon, which is ridiculous," Mannino says. He adds that had he known the real number, he would not have bought the car.
Official gas mileage numbers come from the Environmental Protection Agency. However, David Champion says you shouldn't believe them.
Champion is chief of auto testing for Consumer Reports. He says the EPA's numbers are unreliable because they're based on a test done in a lab, not in real-world traffic. Plus, the test that is used was last updated 20 years ago.
"You really end up with a number, especially a city number, that really is not accurate for today's driving," Champion says.
That's why Consumer Reports does its own gas mileage test on every car it reviews. In its October issue, the magazine compares its numbers with the EPA's. Champion showed Koeppen with a Honda Odyssey minivan.
"According to the EPA, you should get 20 in the city, 28 on the highway," Champion says as he starts to conduct a test.
A device attached to the engine calculates the gas mileage. With the air conditioning turned off, Champion and Koeppen hit the track. Champion says the course simulates typical city driving.
"This is not a particularly stringent test," Champion says. "There's a lot of acceleration, quite a lot of braking, quite a lot of idling."
Next, Champion tested for highway mileage.
"Basic highway driving, 65 miles per hour," Champion says.
In the results of his test, the highway numbers matched the EPA's exactly. The city numbers were a different story. The EPA said it should get 20 miles per gallon. It only got 12.3.
Champion says 12.3 is a "huge" disappointment. "You're gonna be putting almost twice as much gasoline in the car as you thought you would."
He says the city numbers were off in almost every vehicle they've tested. The EPA rated the Ford Focus sedan at 26 while Consumer Reports got 17. The Toyota Camry? EPA got 24, Consumer Reports got 16. The Chevy Trailblazer EXT was 15 versus 9.
But some of the most startling differences were found in hybrids. Take the popular Toyota Prius.
"The Prius, they said, should get 60 miles per gallon in the city," Champion says.
Consumer Reports got 35.
Margo Oge, the EPA's director of transportation, admits there is no perfect test. She says updates to its gas mileage test are in the works to make it more realistic. In the meantime, she says consumers shouldn't believe its numbers are exact.
"If they look at the details of the label, it says this is an estimate, and you will have a range," Oge says.
That's only disclosed in the fine print, something Tom Mannino never read. Now he says he's stuck with a Honda that burns gas like a Hummer.
"Don't tell me I'm gonna get 21, and I'm getting 14," Mannino says. "What's it costing me just to go around town? It costs me a lot of money."
Consumer Reports and the EPA agree that if you're shopping for a new car you can use these numbers to comparison shop. If a sticker says one car has higher gas mileage than another, that will be true.