BYD, one of the world’s largest electric bus manufacturer, boasted recently that its zero-emission buses already covered more than 13 million miles (21 million km) in the U.S.

The buses sold in North America are made in Lancaster, California, where local transit agency — the Antelope Valley Transit Authority (AVTA) — just crossed the 3-million-mile mark of zero-emission operations using BYD buses.

Overall, the company sold buses to more than 50 customers across the country. According to BYD, the total mileage translated into: