In cities worldwide, buses are morphing into giant battery-powered rolling computers. Equipped with the same technologies as the luxury Tesla sedan, they offer a clean, quiet ride for the price of a bus fare.

An expanding fleet of electric and fuel cell buses is taking to urban streets in several countries, notably the United States and China. These buses have higher sticker prices, but because they don’t burn fossil fuels, they cost less to operate and help clean the air.

Zero-emission buses are tapping innovation aimed mostly at cars and deploying it more rapidly. Buoyed by government funds for green public transit—even America’s iconic yellow school bus—their numbers are soaring.

“We’re starting to see a breakout point,” says Bill Van Amburg, senior vice