The company unveiled its EcoRide BE35 at its plant in Greenville, S.C., on Dec. 16.
The bus will offer a fivefold improvement in fuel efficiency compares with a diesel bus and can yield operating savings of more than $400,000 over the lifetime of the bus.
"Proterra is excited to see the first EcoRide BE35 bus rolling off our new assembly line," said Jeff Granato, CEO of Proterra.
If it passes the FTA tests, Proterra will start selling the bus commercially.
The company has already received interest from transit agencies in the United States.
The bus contains all electric components, including an electric drive motor that allows for faster acceleration than a conventional bus, the company said.
Still, the vehicle can only operate for three hours without being plugged in.