Every day, Coca-Cola trucks slowly weave their way through New York traffic, eventually stopping at up to 18 grocery stores, restaurants, and bodegas. As a truck makes a delivery, the engine idles, burning fuel and spewing fumes.

But as of Wednesday, Coca-Cola Enterprises started to do things differently in New York. It is using hybrid delivery trucks, which operate just like the cars, using a combination of batteries and horsepower. When the trucks are unloading, there will be no fumes and idling diesel engines.

Instead, the shiny new red-and-white trucks will have 32 percent better fuel economy. And the hybrids' greenhouse-gas emissions will be 90 percent less than those from regular trucks, according to the manufacturer of the new vehicle.

"It's a small step, but it's one of those steps that if we keep taking, we will be leaving a better world for our kids," says Mayor Michael Bloomberg.

Coca-Cola's transition to hybrid trucks is part of a push by urban delivery companies to cut their greenhouse-gas emissions. As with the hybrid cars, demand for the green trucks is so strong that companies such as Coca-Cola are willing to pay a 35 to 40 percent premium over the cost of a normal delivery truck. Both FedEx and UPS are also building hybrid fleets in urban areas. In return, the companies cut their fuel consumption.

"You get a return on the investment, but more importantly, it's the right thing to do," says John Brock, president of Coca-Cola Enterprises in an interview at the company's giant distribution center in the South Bronx.

Environmental groups, who have pressed for cleaner air to deal with various health issues, are pleased to see the shift. The Coca-Cola distribution center, for one, is in a heavy industrial area with many trucks on the road. Medical testing has found high rates of asthma among local residents.

"That area has some of the nation's highest asthma rates, so looking for ways to reduce vehicle emissions is good," says Jason Babbie, senior environmental policy analyst at NYPIRG, a nonprofit policy lobbying group in Albany. "This is definitely a positive step."

Groups trying to promote corporate responsibility think it's a good example as well. "It's managing a regulatory risk," says Allison Hannon of the Climate Group, which tries to get businesses and government to work together on climate issues. "There is going to be a price on carbon, the cost of energy is going to go through the roof, and for some companies, it will catch them by surprise."

Cutting down on greenhouse-gas emissions in urban areas is considered an important step in slowing climate change, since urban areas account for as much as 80 percent of the gases. "It's where you can make the biggest difference," says Ms. Hannon, who is based in New York.

Shifting over to the hybrid delivery trucks could be one way to cut down on emissions. For example, the average Coca-Cola truck in New York logs 44,000 miles a year on the city's streets. Because of traffic, it frequently does not get above 30 miles per hour, which is hardly fuel efficient.

"This really is a big deal," says Mr. Bloomberg, who has his own plan to dramatically reduce New York's greenhouse-gas emissions.

UPS, with one of the largest truck fleets in the nation, has purchased 50 hybrids for short-haul deliveries. It estimates that on an annual basis, it will save 44,000 gallons of fuel and will cut emissions by 457 metric tons of carbon dioxide. FedEx is also operating 75 hybrids for short hauls.

By the end of the year, Coca-Cola will have five hybrid trucks on the streets. By the end of next year, it will have 120 nationwide. It would like to add more, but, Brock says, "it's a question of capacity" by the manufacturers.

The Coca-Cola trucks are made by International Truck and Engine Corp., and the hybrid system is supplied by Cleveland-based Eaton Corp. Eaton went into full production in July and says it's now ready to produce as many as companies want to order.

"But there are some limitations with the OEMs [original equipment manufacturers, such as International] and how many they can build," says Ken Davis, vice president of light/medium duty transmissions at Eaton Corp. in Kalamazoo, Mich.

As more companies buy the hybrids, the cost will start to come down, says Mr. Davis. "We have a very aggressive program to get the cost down over the next three years," he says.

The potential market for the hybrids, Davis estimates, is about 15,000 trucks per year, or about 10 percent of 150,000 trucks produced annually. "But who knows. It could go to 15 to 20 percent depending on the cost of fuel," he says.

Coca-Cola and its archrival PepsiCo are starting to push each other on a green agenda. Earlier this year, Pepsi announced a significant investment in renewable power – equal to the total amount of energy used by the company's US operations. And Pepsi is now testing hybrid delivery trucks, Davis says. "Stay tuned," he says.