At the grocery store, Lloyd Lachow buys organic milk and fruit. At the dealership, he shops for hybrids.

"It's a cultural thing," Lachow says. "I'm somebody who doesn't think global warming is a myth. I understand what science is. I take those things seriously and act accordingly."

Lachow, 55, is a baby boomer. The generation, born in the years between the end of World War II and the early 1960s, has driven every major automotive buying trend since the late 1970s, when boomers began giving up on Detroit's gas-guzzlers. They flocked to the small, boxy imports built by Toyota and Honda.

In the 1980s, they dissed station wagons in favor of minivans. As their wealth grew during the decade, they moved up to sexier and brawnier sport-utility vehicles to carry their growing families, their shopping bags and their boats. Along the way, they left behind the luxury of Lincoln and Cadillac for the foreign marques of Acura, Mercedes-Benz, BMW and Lexus.

Now, the boomers could be on the verge of making another major turn. After decades of indifference, they are starting to change their buying habits in response to global warming. And automakers are rolling out a growing list of vehicles to take advantage of the changing attitudes.

Environment-conscious consumers have choices beyond the Toyota Prius and Honda Civic hybrids, such as other hybrids, diesels, high-mileage small cars with traditional gasoline engines, and ethanol-powered vehicles. Lachow, a Toyota devotee since the early 1990s, bought a Toyota Camry hybrid last year, a decision he says was motivated by concern over the environment.

Green drivers can find a cadre of subcompact, conventional gasoline-powered cars like Toyota's Yaris and Honda's Fit, which burst onto the U.S. market as hot sellers last year.

Hybrids, which even recently were viewed as a fad, are gaining traction in the marketplace. Toyota's Prius, of course, is king of the category. Toyota expects to sell 150,000 Prius cars this year, up 50 percent from last year. Tight supply had forced would-be buyers onto month-long waiting lists, but now the supply is more plentiful. Dealers say the automaker is intent on pushing hybrids -- including the Prius -- into the mainstream U.S. auto market. Toyota has sweetened deals on the Prius, enticing new customers like Joe Morra, a government attorney who lives in Rockville. Earlier this month, Morra was weighing the purchase of a new Prius at Lake Forest Toyota in Maryland.

"I'm almost 50 years old," Morra said. "I was raised at the tail end of the 1950s, when environmental activism was born. Concern for the environment has been instilled in me my whole life. I recycle. I plant trees. I am a member of the Wildlife Fund. I view owning a car as a necessary evil."

Toyota also sells the Highlander hybrid SUV, while Ford has the Escape and Mercury Mariner hybrids. The hybrid sedan market got a boost recently with the introduction of a hybrid-powered Nissan Altima. Saturn's Aura hybrid sedan is on the way.

Lexus is the sole luxury brand pushing hybrids, but the move hasn't engendered a lot of love from environmentalists, who complain the company is focusing on performance over improving fuel economy. Lexus has the GS 450 hybrid ($55,000) with 340 horsepower that accelerates to 60 miles per hour in the five-second range. It also has the upcoming LS 600h, the first hybrid system tied to a powerful V-8 engine. Typically, automakers take advantage of a hybrid's electric motors to fit vehicles with smaller gasoline engines, cutting down the use of fuel.

"Instead of taking the opportunity to put in a smaller, more fuel-efficient engine, Lexus put in big, gas-guzzling engines, giving you even more power than you had and in many cases more power than most people will ever use," said David Friedman, research director for the clean-vehicles program at the Union of Concerned Scientists. "If we focus our hybrids on keeping fuel economy steady and boosting power, we are going to be spending a lot of money to run in place. That's what we've been doing for the past 20 years."

A hybrid truck category is building momentum, too. General Motors plans to roll out its highly anticipated hybrid versions of the Chevrolet Tahoe and GMC Yukon this year.

Consumers also can find flexible-fuel vehicles, which can run on a fuel blend of 85 percent ethanol and 15 percent gasoline. The use of corn-based ethanol has the potential to reduce greenhouse gas emissions from vehicles by 10 to 20 percent. Other biofuels in development have the potential to cut global-warming gases by as much as 80 percent. But environmental groups question the benefits of ethanol largely because the factories that produce it emit their own greenhouse gases. And fewer than 1,200 of the 176,000 fueling stations in the country sell E85. Most are in the Midwest.

Natural gas is making its way into the commercial car market. One vehicle, Honda's Civic GX, is powered by the clean-burning fuel. The car is available only in New York and California, where it's easiest to find stations that dispense the fuel. There are a few more than 700 stations in the country that sell natural gas as a car fuel.

Mercedes-Benz is betting on luxury diesel sedans. Diesels emit 15 to 20 percent less carbon dioxide per mile than gas-powered vehicles, when taking into account the fuel production. Mercedes's E320 BlueTec diesel sedan ($52,000 sticker price) gets 32 miles per gallon on the highway and 23 in the city.

Diesel models are a tricky option for the earth-conscious, however. Although they cut down on emissions of global-warming gasses, their dirty exhaust has long been a top public-health concern. Auto companies think they can overcome these challenges with better engine technology and cleaner fuel. European nations have moved to diesels to meet carbon dioxide reduction targets. Volkswagen, BMW and Honda have all pledged to expand their diesel lineups in the U.S. market.

Susan Gayle of Arlington bought an E-320 diesel in January. The 51-year-old financial services executive had promised herself that her next car would be better for the environment.

"Maybe its my age or just having a grandson," Gayle said. "He's almost 2. I hope the resources are there so he's able to drive and the other natural resources are in good condition -- the water and the air. I really didn't think about it before until recently."

Gayle says she ignored the warnings and horror stories from friends about diesels -- difficulty in finding diesel pumps, the slow starts and the noise. "I'm finding it's not hard to find the fuel," she said. "They don't make noise, and they start up right."

Some buyers of hybrid cars aren't motivated solely by altruism. Federal tax credits for their purchases also figure into the picture. The credit ranges from $250 to several thousand dollars, depending on the hybrid vehicle and when it is bought. The government limits the allotment of credits available to each manufacturer. It's too late, for example, to get the full $3,150 credit on a 2006 or 2007 Prius because Toyota sold so many last year. The Internal Revenue Service lists the available hybrid tax credits on its Web site, http://www.irs.gov.

But some perks for owning a hybrid are vanishing. Some carpool lanes in Virginia no longer allow hybrids carrying just the driver -- a benefit once enjoyed by hybrid owners -- because of complaints that the gas-electrics were causing crowding. A special tax credit in Virginia for hybrid buyers is also being phased out after the current filing season.

Fuel-economy expectations for hybrids are also being reset. The Environmental Protection Agency has instituted new testing guidelines that try to better take into account real-world driving conditions. The change means significantly lower fuel-economy ratings for hybrids. The Prius, which was rated at 60 miles per gallon for stop-and-go city traffic, gets 48 miles to the gallon under the new system. In highway driving, the Prius rating fell from 51 miles per gallon to 45 miles per gallon.

Americans, who make up about 5 percent of the world's population, are responsible for 45 percent of the world's carbon emissions from cars and light trucks. In studies, focus groups and surveys, Americans are increasingly showing that they understand global warming and want to do something about it, according to Madelyn Hochstein, a trends analyst at DYG, a social and marketing research firm of Danbury, Conn. She pointed to Gallup data showing that 74 percent of Americans in 2006 said that they had a good understanding of global warming, up from 53 percent in 1992.

She characterized today's boomers as carrying an "idealism gene" from the 1960s and early 1970s. Boomers went though a "quality of life" period in the 1980s and 1990s -- a period in which they wanted to be pampered and indulged, she said. Their worldview changed after the terrorist attacks in 2001, and they began to pay closer attention to national and international issues. One area of focus concerns fossil fuels: energy consumption, energy independence and global warming.

"The environment is meshing more and more with economic issues themselves," Hochstein said. Boomers "see these environmental issues as part of the problem, not some separate thing to focus on."

Today's environmentalism differs from saving the whales and the rainforests or patching the hole in the ozone layer, Hochstein said. People today are more likely to express their commitment on a more personal level -- through the choices they make about consumption.

She likens the Toyota Prius to the organic produce sections in grocery stores. Hochstein, who advises BMW, thinks Americans are on the verge of making a stronger commitment to the environment, one that calls for a more socially responsible approach in the use of natural resources.

"I do believe there will be more consumer demand coming for vehicles that respect this new ethic," Hochstein said.

Daniel Gorrell, an expert in car-buyer psychology based in San Diego, sees a coming era of preening and pretentiousness related to the environment. "Buying a car is usually 90 percent related to you," Gorrell said. "It's not about saving the world. It's about making a statement about yourself and your values and that you are caring and conscientious. 'Hey, look at me -- I'm somebody who's special.' "