Next Generation Electric Hybrid Buses Featuring Allison Transmission’s eGen Flex™ Arrive at IndyGo

INDIANAPOLIS, June 15, 2022 – Allison Transmission is pleased to announce that in partnership with GILLIG and Cummins, the first buses equipped with its Allison eGen Flex™ electric hybrid propulsion system have arrived at the Indianapolis Public Transportation Corporation (IndyGo).

The eGen Flex is the next generation of Allison’s proven H 40 EP™ electric hybrid propulsion system, which has been operating in select IndyGo buses since 2004. In addition to the benefits provided by the H 40 EP, such as improving fuel consumption by up to 25% versus a conventional diesel bus, the eGen Flex provides revolutionary capabilities which include full electrification range.

“IndyGo’s continued collaboration with Allison represents our joint mission and commitment to reduce our carbon footprint in the Indianapolis community,” said Inez Evans, IndyGo President and CEO. “The delivery of the GILLIG buses equipped with the eGen Flex technology represents the next step in our efforts to reduce our dependence on fossil fuels, enhance quality of life for residents and do our part to protect the environment.”

The eGen Flex, which is paired with the Cummins B6.7 engine in GILLIG buses, is capable of traveling in electric-only mode for up to 10 consecutive miles or 50 minutes before converting back to hybrid propulsion. This electric-only mode can be utilized multiple times per route and per day. The eGen Flex can operate up to 50% of the time in engine off mode while still powering auxiliary systems like air conditioning and heat at optimal efficiency. The system’s electric-only mode is activated through geofencing technology and eliminates engine emissions and noise while loading and unloading passengers in dense pedestrian areas, zero-emission zones and at Indianapolis’ public transportation hub, the Julia M. Carson Transit Center.

“Allison understands that while there is significant interest in electrification, many transit agencies face challenges in adopting fully electric solutions. The eGen Flex enables fleets to evaluate full electric capability while maintaining a diesel engine for added flexibility,” said David Graziosi, Chairman and CEO, Allison Transmission. “We’re proud to continue our long-term partnership with IndyGo to provide a solution that will reduce CO2 emissions and help protect the environment right here in Indianapolis, the hometown of Allison’s global headquarters.”

IndyGo will be the first transit system to operate GILLIG buses equipped with the Allison eGen Flex and Cummins B6.7 engine pairing. The delivery was celebrated during an event in downtown Indianapolis yesterday evening.

Jun 16, 2022


Allison Transmission (NYSE: ALSN) is a leading designer and manufacturer of vehicle propulsion solutions for commercial and defense vehicles, the largest global manufacturer of medium- and heavy-duty fully automatic transmissions, and a leader in electrified propulsion systems that Improve the Way the World Works. Allison products are used in a wide variety of applications, including on-highway trucks (distribution, refuse, construction, fire and emergency), buses (school, transit and coach), motorhomes, off-highway vehicles and equipment (energy, mining and construction applications) and defense vehicles (tactical wheeled and tracked). Founded in 1915, the company is headquartered in Indianapolis, Indiana, USA. With a presence in more than 150 countries, Allison has regional headquarters in the Netherlands, China and Brazil, manufacturing facilities in the USA, Hungary and India, as well as global engineering resources, including electrification engineering centers in Indianapolis, Indiana, Auburn Hills, Michigan and London in the United Kingdom. Allison also has approximately 1,600 independent distributor and dealer locations worldwide. For more information, visit