Carmakers are responding to consumers who want more environmentally friendly vehicles. By Mark Solheim, Editor May 1, 2007 I didn't go to any environmental rallies or cleanups on Earth Day. Rather, I showed my support for a cleaner environment in a way better suited to a car journalist: I test-drove the new Nissan Altima Hybrid.While getting a respectable 42 miles per gallon in the city and 36 mpg on the highway, the Altima Hybrid spewed far fewer greenhouse gases -- the ones linked to climate change -- than a comparably powered gas-engine-only sedan would have. Besides leaving a smaller carbon footprint, the Altima Hybrid, in the techno-speak of the emissions intelligentsia, is an Advanced Technology -- Partial Zero Emissions Vehicle. That means it releases almost no "evaporative" emissions -- the kind you get when gasoline evaporates and releases hydrocarbons, which react with sunlight to form smog. Sponsored Content RELATED LINKS New Hybrids Debut No-Gas and Low-Gas Cars More models Okay, neither the Altima nor any other hybrid is totally guilt free, and maybe I should have ridden my bike to pay homage to planet Earth. The point is, hybrids are more environmentally friendly than any other mass-market alternative. Diesels still are struggling to meet emissions standards in a number of states. Ethanol is still too expensive to produce, and affordable plug-in-battery technology is still a few years away. Advertisement Hybrids are far more plentiful now than they were even a year ago. Toyota sold nearly 107,000 Priuses last year and expects to sell 150,000 in 2007, on top of projected sales of about 60,000 Camry hybrids and 60,000 other Toyota and Lexus hybrid models. Honda's Civic Hybrid is also selling well. And more are on the way from other brands as carmakers sense the need to appease car buyers who want less pain at the pump and less impact on the environment. In one of the first public mea culpas from a top automotive executive, Ford CEO Alan Mulally recently admitted that global warming is real and caused in part by auto emissions. "Being stewards of our environment," he said, "is the biggest agenda we have at Ford." Ford currently sells the Escape and Mercury Mariner hybrid SUVs, and it has plans to introduce a Ford Fusion and Mercury Milan hybrid sedan. Nissan is the latest carmaker to produce a hybrid. However, the company seems ambivalent about the technology: The Altima Hybrid is sold only in California and the seven states that follow California's emissions standards. Saturn is now churning out its Green Line Aura sedan and Vue SUV. And Chevy plans a Malibu sedan and Tahoe SUV hybrid later in the year. (SEE OUR SLIDE SHOW of the five hybrids introduced within the past year.) Advertisement Hybrid economics What's held back many potential hybrid buyers is the price premium over comparable gas-engine sedans. Unless gasoline prices go a lot higher than they are now, you're not likely to earn back the premium you'd pay for a hybrid car with savings at the pump. When you compare the cost of a hybrid with its gas-engine doppelgänger, hybrids typically cost several thousand dollars more. In 2006 Uncle Sam began offering more-generous tax breaks -- a dollar for dollar credit to your tax bill -- to hybrid buyers. Some states and local governments also offer incentives (including sales-tax breaks and solo driving in HOV lanes). When you add savings on gas to the federal credit and incentives, a couple of hybrid models -- notably the Toyota Prius and Honda Civic Hybrid -- come close to paying back their premium, especially when you look at overall owner costs over five years. The Toyota Camry and Nissan Altima hybrids are the closest runners up. Based on fuel economy, the federal tax break ranges from a one-time credit of $250 for the two-wheel-drive Chevy Silverado and GMC Sierra -- which improve gas mileage only 10% to 15% -- to $3,000 for the 2wd 2008 Ford Escape and Mercury Mariner hybrids. The Prius used to top the tax credit list, but Congress in its inscrutable wisdom limited the full credit for hybrids to the first 60,000 vehicles sold by a manufacturer. In the phaseout of the break, credits for Toyota and Lexus hybrids have been halved and halved again. If you buy a Prius before October 1, 2007, you'll be eligible for a $787.50 credit. After that, you get nothing. For a complete list of credits, go to the Department of Energy's fueleconomy.gov Web site.