While some technological challenges remain, the market is heating up.

　　This hydrogen fuel cell vehicle from Toyota converts hydrogen into electricity, has a smooth ride, strong accelertion, and leaves no carbon monoxide behind.

　　“We think that hydrogen is the future of electric vehicles because they’re so much more convenient," said Toyota's Wade Hoyt. "And the way it works is that the hydrogen wants to combine with the oxygen in the air. It forms H2O, which is water vapor, is the only exhaust, so it’s a true zero emissions vehicle. And you get electricity out of that combination.

　　Many manufacturers are now producing hybrids and electric vehicles. Ford has unveiled an all-electric Ford Focus and Chevy is touting its environment-friendly Volt. While electric cars are easy on the environment, they can also offer strong preformance. Tesla's has ferocious acceleration, pushing the car from zero to about 100 kilometers per hour in three-point-seven seconds, with a top speed just over 200 kilometers per hour. Electric motors deliver strong acceleration because they offer more torque than equivalent gasoline engines. That is why luxury brands, like BMW, are experimenting with this new technology.

　　But the switchover from gasoline is an evolutionary process, says James Bell of General Motors.

　　"I think the mistake that many people in the industry and in the media maybe thought was that -- when the Nissan Leaf came out or the Chevrolet Volt -- was that suddenly people would drop their gasoline cars and rush for them. No, it’s not that way," he said. "This is going to be a slow evolution, but it’s also a Pandora’s box moment. It’s not going to go back in. Electrified vehicles are the way to meet those emissions in the future.”

　　Alternative fuel vehicles account for just one million of the than 60 million cars produced worldwide annually. But in 2013 the number of hybrid and electric cars doubled. Automakers still don’t make money on electric cars because of the high cost of battery technology. Tesla's battery, for example, costs $50,000, about half of the vehicle’s total selling price. But manufacturers pay the costs because they believe electric vehicles are an important part of the industry's future.

　　Matt Miller, auto industry reporter for Bloomberg News, says a mixture of old and new technology is the winning strategy.

　　“Really the key for the future, I think, is hybrid technology, so rather than having a car like a Tesla, completely electric-powered, you have a car like the BMW I-3 or I-8, which has a small gasoline motor to help charge the battery when it’s needed and electric motors to drive," he said. "That’s got to be the future. Then you get something like 90 or 100 miles per gallon, [19 to 21 kilometers per liter] which is decent and you still get the torque when you need it.”

　　The challenge is to produce a car with long, inexpensive battery life that allows the driver to travel a long way between charges. Automakers expect many millions will then decide to switch from gas to alternative fuel.