Proterra’s battery-electric bus can recharge in 10 minutes (Photo: Proterra)

General Motors is investing 6 million dlrs in Proterra, a maker of zero-emission commercial transit buses.

The investment comes from funds the automaker has earmarked to identify and help develop innovative new transportation technologies.

GM said its GM Ventures division is part of an investment group led by venture capital firm Kleiner Perkins Caufield & Byers that will invest a total of $30 million in the bus manufacturer.

"While this investment will help Proterra commercialize its electric bus and fast-charging technology, it also helps to address the future challenges of urban mobility,” GM Ventures President Jon Lauckner said in a press release.

Proterra was founded in 2004 and is currently manufacturing buses in a temporary plant in Greenville, South Carolina. A test fleet of three of its EcoRide BE-35 buses is running near Pomona, California. Other tests are planned.

The EcoRide BE-35 battery electric buses average up to 24 mpg (diesel equivalent) in service, a more than 600-percent improvement over a typical diesel bus. The lightweight, composite-body buses recharge in about 10 minutes, using Proterra’s TerraVolt energy storage system. Energy is provided by 54-72 kWh lithium titanate battery packs.

GM said the combined new investment will allow Proterra to complete federal validation testing of its bus and roll out the additional pilot fleets. It will now also complete initiatives to significantly reduce costs and increase volume production in Greenville. Proterra's plant will have capacity toproduce 400 buses annually.