Two of the family's biggest energy drains stand in the driveway: a 1998 truck that gets 13 to 15 miles per gallon and a 2002 van that gets just 10 to 12 miles per gallon. Together the two gas guzzlers were driven almost 20,000 miles in the past year, generating more than 30,000 pounds of greenhouse gases. Evelyne approves the Perez plan to "run them into the ground" before replacing, "and by then there will be even more electric and hybrid options," she says, with federal tax credits available for some models. But she also points out that maintaining a vehicle properly makes it more fuel-efficient. The manufacturer's recommendation for tire inflation (in a unit of measure called PSI, or pounds per square inch) is often written inside the door frame or in the owner's manual. Tires can lose about a pound of pressure in a month, and for every three pounds below the recommended pressure, fuel economy goes down by about 1 percent. The NRDC estimates that if all Americans kept their tires properly inflated and bought replacements of the same quality as the originals, we would save more oil than is available in the Arctic National Wildlife Refuge. How you drive is important, too: Flooring the gas pedal and braking hard dramatically decrease gas mileage and lead to more pollution. According to the American Council for an Energy-Efficient Economy, one second of high-powered driving can produce nearly the same volume of carbon monoxide emissions as a half hour of normal driving. Speeding along at 75 miles per hour instead of 65 lowers your fuel economy by about 10 percent. And carrying around an extra 100 pounds of cargo reduces fuel economy by about 1 percent.

Perhaps the most important message for the Perez family—and possibly yours—is about looking beyond one's own backyard. The leaders of more than 600 American cities have signed the U.S. Mayors Climate Protection Agreement, launched in 2005 with a goal to cut greenhouse gas emissions. Portland, Oregon, has built hundreds of miles of bike paths. Austin gave tax breaks for green homes and businesses. Salt Lake City converted more than 200 traffic signals to energy-efficient bulbs. If your hometown isn't on the list at, Laurie suggests writing to your mayor. San Clemente is not part of this admirable action plan—in fact, the Perezes must go to another town just to recycle—so a letter is in the mail.