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Allison Transmission Earns Certification from California Air Resources Board for eGen Flex™ Electric Hybrid Propulsion System

Allison Transmission today announced it has received certification from the California Air Resources Board (CARB) for the model year 2022 eGen Flex™ electric hybrid propulsion system paired with Cummins B6.7 and L9 engines. Since 2014, Allison has received annual certification from CARB for the Allison H 40/50 EP™ propulsion system. For the first time this year, the certification was awarded for the eGen Flex, the company’s newest electric hybrid solution for transit buses and coaches.

Introduced in 2020, the eGen Flex electric hybrid system is capable of traveling in electric-only mode for up to 10 consecutive miles or 50 minutes. This electric-only mode can be utilized multiple times per route and per day. In real world revenue service, Allison’s eGen Flex has demonstrated the ability to operate in full engine off mode for more than 50% of its time in operation across multiple routes within one of North America’s largest transit fleets. The eGen Flex is further capable of eliminating engine emissions and noise while loading and unloading passengers, in dense pedestrian areas, and in zero emission zones and bus depots. In addition, the eGen Flex improves fuel consumption by up to 25% versus a conventional diesel bus.

“We are thrilled to receive CARB’s certification for the eGen Flex, Allison’s latest innovation in electric hybrid propulsion technology,” said Barbara Chance, Director of Mobile Source Regulatory Compliance for Allison Transmission. “The H 40/50 EP legacy system was the first electric hybrid propulsion system to be certified in California for transit buses and coaches. We’re honored to now collaborate with CARB to earn certification for the eGen Flex, which provides revolutionary capabilities for public transit.”

The Cummins B6.7 and L9 diesel-electric hybrid engines feature proven technology designed and developed in-house that is optimized to deliver the efficiency, durability and performance on which transit bus customers depend. The B6.7 diesel-electric hybrid engine is rated at 280 hp (209kW) while the L9 diesel-electric hybrid engine is rated at 330 hp (246kW) for the transit bus market.

“Cummins is excited to have received the necessary CARB certifications for the integration of our engines into Allison’s next generation electric hybrid propulsion system,” said Francisco Lagunas, General Manager, North America Bus Business, Cummins Inc. “We believe the latest Cummins and Allison clean diesel power system will provide our bus customers an even more reliable and environmentally-friendly powertrain to help them be as successful as possible.”

About Allison Transmission

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 more than 1,400 independent distributor and dealer locations worldwide. For more information, visit

About Cummins

Cummins Inc., a global power leader, is a corporation of complementary business segments that design, manufacture, distribute and service a broad portfolio of power solutions. The company’s products range from diesel, natural gas, electric and hybrid powertrains and powertrain-related components including filtration, aftertreatment, turbochargers, fuel systems, controls systems, air handling systems, automated transmissions, electric power generation systems, batteries, electrified power systems, hydrogen generation and fuel cell products. Headquartered in Columbus, Indiana (U.S.), since its founding in 1919, Cummins employs approximately 59,900 people committed to powering a more prosperous world through three global corporate responsibility priorities critical to healthy communities: education, environment and equality of opportunity. Cummins serves its customers online, through a network of company-owned and independent distributor locations, and through thousands of dealer locations worldwide and earned about $2.1 billion on sales of $24.0 billion in 2021. See how Cummins is powering a world that’s always on by accessing news releases and more information at


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