Long after the first predictions were made of how solar or wind power or rechargeable batteries would replace fossil fuels, gasoline and diesel engines are still the predominant energy source in commercial work trucks. Those great ideas are coming but they are not here yet. First something becomes possible, then it becomes economical, and finally it becomes well-designed and ready for widespread acceptance. Eventually, the future arrives. But rarely as quickly as predicted. New technologies can yield huge leaps of improved efficiency, but the learning...