With the exception of the upcoming, lease-only Smart EV, Mercedes-Benz has been almost absent from the electric-car movement. But that's not to say their advanced alternative fuel activities are dormant. Rather than field battery-powered cars, the automaker has been focusing on more forward-reaching technology: fuel cells. (A fuel-cell car is essentially an EV with an on-board electricity generating ability.)

At the 26th Electric Vehicle Symposium (EVS26) in Los Angeles this week, Mercedes had two hydrogen fuel-cell-powered B-Class hatchbacks, a small-yet-tall car not sold in the United States in its traditional form. The fuel-cell B-Class has been for lease in California for nearly two years, providing Mercedes real-world feedback from customers. (We tested a gasoline-powered B-Class in 2007.)

The fuel-cell B-Class lease payment is $849 a month, which includes hydrogen fill ups. The B has a claimed range of 200 miles and stores 3.5 kilograms of hydrogen at 10,000 psi. That works out to be about 57 miles per kilogram consumption.

Retail prices for a kg of hydrogen are not firmly established, so it's hard to make cost comparisons to gas or electricity. It takes 5-10 minutes to fill up the tank, according to Mercedes. A 1.4-kWh battery buffers the fuel cell and gets regenerated by coasting and braking. The B-Class drove much better than the fuel-cell A-Class, a previous Mercedes' research vehicle that I drove in 2007. This one felt solid and quiet, and it delivered an effortless surge of power.

The car and powertrain technology has clearly progressed, but the hydrogen infrastructure has not expanded much in the last five years, remaining a critical challenge to expanding the reach of fuel cells.

See our guide to fuel economy and guide to alternative fuels.

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