Proterra, a major player in heavy-duty electric transportation, has closed a $55 million funding round with new investors BMW i Ventures and Al Gore’s Generation Investment Management. The company plans to utilize the investment to increase production at its manufacturing facilities in South Carolina and Los Angeles, while also bolstering research and development efforts at the company’s headquarters in Silicon Valley.

The new investment comes six months after the company raised $140 million to build its second factory. Proterra currently holds 60 percent market share in the North American electric transit market.

The company is known for its composite-intensive electric buses, the Catalyst XR and Catalyst E2. In 2015, the Catalyst XR drove 258 miles on a single charge under test conditions at Michelin’s Laurens Proving Grounds. The company says the 40-foot-long Catalyst XR has already achieved the highest efficiency rating ever for a transit bus of it size, which is equivalent to a gas vehicle averaging 22 mpg.

According to Joshua Stewart, senior manager of mechanical engineering at Proterra, the XR’s lifespan can be either 12 years or 500,000 miles, whichever comes first. GFRP is utilized in many areas of the main body, with CFRP selectively employed in areas where the bus needs a high strength-to-weight ratio, such as the A-pillars, areas surrounding the window cutouts and some of the lower body structures. The composite parts were made with vacuum assisted resin transfer molding (VARTM). Each structure is built with an upper and lower mold, which are fabricated and then bonded together.

The E2 was unveiled in 2016. The bus’s 660kWh battery pack, combined with its carbon fiber reinforced polymer (CFRP) body, has allowed it to achieve a range of up to 350 miles in a single charge. In total, the bus weighs just shy of 15 tons. In August 2016, an E2 series vehicle achieved a new milestone at Michelin’s Laurens Proving Grounds where it logged more than 600 miles on a single charge under test conditions. It has a nominal range of 194 – 350 miles, which means the Catalyst E2 bus series is capable of serving the full daily mileage needs of nearly every U.S. mass transit route on a single charge and offers the transit industry the first direct replacement for fossil-fueled transit vehicles.

As Proterra explained, the investments from Generation Investment Management and BMW i Ventures represent important milestones for both groups. Generation has a long history of investing in mobility, covering a range of sustainable solutions from electric vehicles to bike sharing to fleet management technology. With Generation establishing a presence in San Francisco this year, this is a critical investment to add to their growing portfolio on the West Coast. For BMW i Ventures, this represents its first investment in heavy-duty electric vehicle manufacturing underscoring the transition to electric mass transit. United by a shared belief in responsible citizenship and sustainable transportation technology, Proterra will work closely with Generation and BMW i Ventures to help communities transition to zero-emission mobility fleets.