Proterra has been making electric buses for many years now, and a number of its zero-emission vehicles are part of the public transport system in several US locations. But the company's latest design - the Catalyst E2 series - is pretty special: it can travel up to 350 miles on a single charge.

Proterra showed off the E2 bus at the American Public Transit Association's annual meeting. With a battery configuration that can vary between 440 and 660 kWH, the buses can achieve a nominal range of 194 to 350 miles.

During testing at Michelin's Laurens Proving Grounds last month, the company claims the E2 managed to run for more than 600 miles when fully charged. The vehicle's light frame and regenerative braking system helps it achieve these impressive distances.

The E2's range means it could run virtually any bus route for an entire day without needing to stop for a recharge. "Proterra's primary goal has always been to create a purpose-built, high-performance electric vehicle that can serve every single transit route in the United States," said Proterra CEO Ryan Popple.

As is often the case with cutting-edge tech, the price of the Catalyst E2 may put off some potential customers. While diesel-powered buses of the same passenger capacity cost roughly $300,000, this zero-emissions model starts at around $800,000.

That price tag may sound pretty eye-watering, but Proterra says the buses' cost is offset by a number of factors. Compared to diesel, compressed natural gas (CNG) and diesel-hybrid buses, the E2 vehicles have 30 percent fewer parts and up to 75 percent fewer brake repairs. And with subsidies available in certain cases, along with no fuel costs and less required maintenance, Proterra says that the E2s can save operators more than $450,000 over a 12-year period when compared to other types of buses.

Passengers should be able to ride the Catalyst E2 buses sometime in 2017.