The Greensboro (N.C.) Transit Authority is buying four 40-foot Proterra electric buses for around $3.84 million.

The buses will replace retiring fossil fuel buses. Over their 12-year lifetime, the buses are expected to generate maintenance and operations cost savings of more than $1.7 million. Greensboro has a five-year contract with Proterra, and expects to buy additional buses as it replaces its full fleet.

The project is funded with transportation bond funds approved by voters in November 2016 as well as federal and private grant money.

Construction is expected to begin in November to install a fast-charging battery station. It will be able to charge a bus battery in six to 12 minutes as the bus drops off passengers and waits for new ones to board. (Watch a video from Proterra on its electric bus technology.)

Proterra says its batteries have a nominal range of 350 miles and can be charged with J1772 CCS plug-in chargers or with overhead charging systems. The drivetrain consists of a 220kW peak permanent magnet drive motor and 2-speed auto-shift EV transmission. The bus can go from 0-20 mph in 4.5 seconds, the company says. The powertrains also include regenerative braking technology.

The bus bodies are made with carbon-fiber-reinforced composite materials that help the bus withstand impacts and corrosion. (Read the spec sheet.)

With an annual total ridership of 6.1 million, GTA provides mass transit services to over nine dedicated routes throughout Greensboro.

Proterra designs and manufactures zero-emission heavy-duty vehicles. To date, it has sold more than 480 vehicles to 60 different municipal, university, airport and commercial transit agencies in 25 states. The vehicles are designed, engineered and manufactured in the U.S., with three-quarters of its components sourced from U.S. locations. Corporate offices are in Silicon Valley, and the company has manufacturing facilities in South Carolina and Los Angeles.