The Chevrolet Equinox mid-size crossovers that are the centerpieces of General Motor's Project Driveway long ago (September 2009) passed a million miles of emisson-free operation. The hydrogen fuel cell stack that powers the 100 vehicles in the program was, at the time of its launch in late 2007, state-of-the-art for GM. It produced some 62 kW of peak electrical power by electrochemically combining hydrogen with oxygen, producing only water vapor from its exhaust pipe. It weighs some 550 lbs (250kg) and is the size of a large suitcase. It is now obsolete.

General Motors has now released the newest iteration of its evolving hydrogen fuel cell 'engine', this one packing even a greater wallop of electric power, but significantly smaller in size, as well as weight and the amount of precious platinum in its catalyst. Called by GM its "second generation" fuel cell, it is half the size of the Project Driveway stack and weighs 282 lbs (130kg). Just as significant, the number of parts has been cut nearly in half and the amount of platinum reduced from 80g to just 30g.

The new stack is now the approximate size of the same four cylinder engine being used in the Chevy Volt to produce electric power for the car once it exceeds the range of its battery pack. This offers the opportunity that sometime around 2015, when GM believes its stacks will be cost competitive with other advanced power trains like plug-in hybrids, for it to replace not only the gasoline engine but also its generator with the new fuel cell stack, significantly simplifying the drive system on the vehicle.

Yet to be solved, however, is the production, distribution and storage of hydrogen, the lightest of all gases. While both the Germans and Japanese have announced initiatives to construct networks of hydrogen stations across their respective countries, the U.S. is taking a more cautious approach, focusing on plug-in hybrids and alternative fuels like ethanol and synthetic diesel and gasoline from coal and natural gas.

Most recently, Honda, which has made a similar strong commitment to fuel cell development, introduced its latest generation of home hydrogen refueling system. At Britain's University of East Anglia, work is progressing to develop technology that uses sunlight to crack water into hydrogen and oxygen, offering the promise storing the energy in sunlight into a more portable energy carrier.