Latest addition is evidence of growing transit demand for lower total lifecycle cost, more sustainable buses

GREENVILLE, S.C., May 21, 2013 – Proterra Inc, the leading provider of zero-emission commercial transit solutions and maker of the world's first all-electric fast-charge transit bus, the EcoRide™, has added San Joaquin Regional Transit District in Stockton, California, to the list of cities currently operating its buses. On Monday, May 20, San Joaquin RTD publicly unveiled its two EcoRide™ buses, funded through a $2.56 million grant from the California Energy Commission under its successful Alternative and Renewable Fuel and Vehicle Technology Program established under California Assembly Bill 118. This latest deployment, the first in northern California, continues Proterra's expansion in public transit. Proterra has more than tripled transit agency orders under contract for the company's flagship EcoRide™ in the past 12 months alone and is planning for its current growth path to continue.

The two composite body buses will operate on RTD's Route 51, which will enable the buses to recharge at RTD's Downtown Transit Center.

"We're excited to be a part of an historic new era of zero-emission public transportation, and we are proud of what we can now offer to those who live and work in our region," said RTD General Manager/CEO Donna DeMartino. "RTD is a local leader in the adoption of technologies that improve the environment and provide better services for our customers and our community."

Proterra executives have worked closely with San Joaquin RTD, the California Energy Commission and CALSTART on this new electric bus project. Proterra's Vice President of Sales and Marketing Ian Shackleton and Chief Business Development Officer and General Counsel Marc Gottschalk and Board Member Michael Linse from Kleiner Perkins Caufield & Byers attended the official launch ceremony on Monday, May 20.

"As the cleanest, most fuel efficient and lowest total cost of ownership option in the transit market, Proterra's all-electric buses are the natural choice for transit agencies struggling to balance budget constraints, ever-increasing fuel costs and mounting sustainability pressures," said Ian Shackleton. "We are thrilled to see our buses go into service in another forward-looking community and proud to have worked closely with San Joaquin RTD and the California Energy Commission to make this project a success. We look forward to having our buses in service there for many years to come and to pointing to RTD's success to lead other agencies to take similar steps toward the future of transit."

About San Joaquin Regional Transit District

The San Joaquin Regional Transit District, the regional transit provider for San Joaquin County, provides public transit services in the Stockton Metropolitan Area, throughout San Joaquin County, and between surrounding communities. RTD's services include Stockton Metro routes, three Metro Express (Bus Rapid Transit) corridors, Intercity service, Metro and County Hopper deviated-fixed routes, Dial-A-Ride, and San Joaquin Commuter interregional routes to the San Francisco Bay Area and Sacramento.

About Proterra

With manufacturing in Greenville, S.C., Proterra is a leader in the clean technology and clean energy space, designing and manufacturing heavy-duty electric drive systems, energy storage systems, vehicle control systems, transit buses and fast-charging stations. Proterra's systems are scalable to commercial buses of all sizes. Its ground-up designs have led to the EcoRide™, the world's first full-size, 10-minute charge battery-electric transit bus. In 2011, Proterra's EcoRide™ became the first heavy-duty electric transit bus ever to complete challenging federally required durability and reliability testing at the Bus Research and Testing Center in Altoona, Pennsylvania, demonstrating best in class energy efficiency and noise levels. For more information on Proterra and its technology, please visit: www.proterra.com