At a landfill near Livermore, Calif., refuse trucks roll up to the dump, drop off trash and refuel with methane generated by the garbage heap.
At the U.S. Department of Energy, more than 7,000 government vehicles run on propane.
And from hybrid taxis in New York to compressed natural gas trucks at U-Haul, virtually every sort of unconventionally powered vehicle can be found in U.S. fleets -- the real-world workhorses for stress-testing green vehicle technology.
Fleets offer a sharp contrast to the retail market, where automakers selling green vehicles must overcome serious obstacles, such as enormous fueling infrastructure needs and ingrained consumer habits.
That makes fleets an appealing initial market for green vehicles -- and, automakers hope, a steppingstone to retail success.
"We are not restricting the availability of any of our technologies to simply the fleet customer," says Gerry Koss, Ford Motor Co.'s fleet marketing manager. "But near term, the interest and demand by fleet may be more than retail."
Ford will bring out the electric Transit Connect van this year, followed by a Focus EV in 2011 and a plug-in hybrid in 2012.
Steven Schneider, CEO of electric vehicle maker ZAP, says fleets that have their own recharging stations are a prime EV market. Consumers worried about limited range will adopt EVs slowly, Schneider says.
"There's no way to put in enough infrastructure in the early years to come that you would not have range anxiety."
But it's not a given that fleet sales will lead to retail success. CNG vehicles have been used in fleets for years without penetrating the consumer market.
Fleet sales, in other words, could be a dead end.
But for now, fleet managers are prime customers for green vehicles. Many fleets have a built-in advantage over individual users. Their vehicles roll out from a central depot in the morning and rack up predictable mileage. Then they roll back into the depot, where they can be refueled or recharged overnight.
Stephen Ellis, American Honda Motor Co.'s manager of alternative-fuel vehicles, describes such fleets as "tethered operations."
Says Ellis: "They have a starting point in the morning, and they have an ending point at night, often the same point."
That means fleet buyers, unlike individual consumers, don't have to wait to see when -- or whether -- a fueling infrastructure appears. Also, fleet managers are under pressure to cut their carbon footprint and fuel costs.
Scott Heyer, fleet sales corporate manager for Toyota Motor Sales U.S.A., says the company sells a lot of Prius hybrids to fleet buyers attracted by the total life cycle cost of ownership.
Prius is our No. 1-selling commercial vehicle right now," Heyer says. "We're actually selling two Priuses for every Camry gasoline vehicle."
The top concern of fleet managers is depreciation, followed by fuel costs -- although those flip when fuel prices rise, Heyer says.
Honda's Ellis says many fleets are under directives to get greener. Major corporations such as AT&T, Comcast and Xerox Corp. tout the green vehicles in their fleets.
"You could almost say they're competing for the green space," Ellis says.
"In my opinion, it's not 'green-washing.' It's a very sincere initiative."
Ken Bernard, chairman of the fuel advisory council of the National Association of Fleet Administrators, says fleet operators aren't just buffing their images.
"They're trying to stay ahead of the emissions curve," says Bernard, fleet manager for the city of Roanoke, Va.
John Righini, chief marketing officer for GE Capital Solutions fleet services, agrees.
"They're getting ahead of it," he says. "All of these folks, including us at GE, are anticipating that greenhouse gas [restrictions] will be legislated."
Still, fleet sales are small relative to retail numbers.
For instance, the largest green fleet -- Merck & Co., the pharmaceutical company -- has 5,849 alternative-fuel vehicles, according a survey this year by Automotive Fleet magazine.
The crucial question for automakers is whether they can use fleet sales as a springboard to big retail volume.
Phil Gott, managing director at IHS Automotive Consulting, thinks so. For automakers bringing out EVs, fleet sales can fill the gap after the first rush of true believers dies down, he says.
"That's really the market that will carry the growth between the early adopters and the mainstream buyers," Gott says.
But analyst Jim Hall cautions that fleet acceptance won't translate automatically into retail sales.
Mainstream retail buyers won't buy alternative vehicles unless a fueling network is in place, he says.
In the case of EVs, that means a nationwide grid of recharging stations.
"I think the gamble is that these things will work so well [in fleets] that there will be a demand for them," says Hall, principal of the 2953 Analytics consulting firm in suburban Detroit.
"Until you get the infrastructure, you can't proliferate beyond central fueling stations."
Penetrating the retail market clearly is the top priority for automakers. Toyota's Heyer says the company develops vehicles mainly for retail.
"Our philosophy is that we're looking for technology that works," he says. "If it works for the retail consumer, it will work for the fleets as well."
Honda's Ellis says fleet sales have secondary benefits, such as allowing automakers to road-test new technologies.
But he qualifies that, saying that with Honda's EV Plus, which it produced in the late 1990s, "we learned more in six months with consumers than we did in two years in fleets."
Adds Ellis: "The holy grail, of course, is consumer sales."
Click here to view the story on Automotive News.