the proterra catalyst be40 is a low floor, battery electric transit bus made by proterra catalyst. it was first made as the 40 - foot catalyst be40 at the 2014 apta bus and paratransit conference in kansas city. foothill transit, the launch customer for the first generation bus, was the first to order the latest generation bus. the be40 has battery electric propulsion. this bus has probably retired from mta nyc transit because it was replaced by the xde40 and the xe40.