Future car technologies will depend more and more on varied sources of fuel and energy-efficient engines with low emission of gases: hybrid cars (which run on gasoline and an electric bettery), electric cars, and the hydrogen carof the future.
The British government with a group of thirteen companies has launched a project to make the hydrogen-powered car a commercial success. They plan to manufacture hydrogen fuel cells for electric vehicle. But in order to make cars attractive to consumers, they need to set up a nationwide refueling infrastructure so that people can easily get fuel. One of the main advantages of the hydrogen car is the "almost zero" gas emission.
As for the price of such energy-efficient cars, we'll have to wait and see. Ford's Model-T cost $850 in 1909, which is the equivalent of $20,000 today. One gallon of gas(3.785 liters) at that time cost twenty cents.
What fuel will be used in cars of the future ? Only time will tell.