In the United States, there are 20 hydrogen-powered BMWs.

One arrived in Westlake Village on Thursday.

Officials with BMW's Oxnard-based CleanEnergy program delivered one of its Hydrogren 7-Series sedans to J.D. Power and Associates for a two-week test drive.

"We're looking for honest feedback," said James Ryan, program director for BMW's CleanEnergy program. "They are very well-known in the industry. Their credibility is beyond reproach."

Only 100 of the H7 sedans exist, each built on an assembly line. None is for sale. Instead, the German car company lends the vehicles to high-visibility eco-friendly ambassadors, such as actors Halle Berry and Brad Pitt, to encourage people to look at alternative fuels.

J.D. Power and Associates has issued an Alternative Powertrain Study, charting the consumers' inclinations toward alternative fuel vehicles for the last two years.

J.D. Power III, the company's founder, said a variety of approaches to alternative fuel vehicles should be developed. He said that as consumers make their buying decisions, they ultimately will decide what will survive in the marketplace.

"In an open market, I think what we want to do is have manufacturers have their opportunity to do it their way," Power said. "You have to have a whole package for the consumer. With the advances in technology, I think the technology moves faster than consumers."

In the case of the Hydrogen 7, which has 30 years of research behind it, as with other alternative fuel vehicles, the infrastructure to support the vehicles moves slower.

It will likely be another 10 years before hydrogen vehicles make inroads into the commercial market because of the shortage of fueling stations to support them, according to BMW.

There are only two liquid hydrogen filling stations in the United States, one of which is in Oxnard. The second is mobile, able to move from city to city. A third is planned in Los Angeles.

The Hydrogen 7 is not an experimental car. It is in its sixth generation since it was introduced in 2001, said Nadine Jambor, program executive for BMW CleanEnergy.

The benefit of the hydrogen vehicle is that it has almost zero emissions. The hydrogen is made from renewable sources, such as electrolysis with water using solar energy. The vehicle's exhaust is water.

Unlike other hydrogen vehicles, which rely on fuel cells, the Hydrogen 7 is an internal combustion car that uses liquid hydrogen. It can also run on gasoline, with drivers getting about 300 miles on a full tank. Using hydrogen for fuel, the car can get about 130 miles on the 18 pounds of hydrogen stored in a tank behind the back seat.