Hyliion Holdings Corp.

Hyliion was founded in 2015 by Thomas Healy in Pittsburgh, Pennsylvania, while studying mechanical engineering at Carnegie Mellon University. The company developed hybrid electric drivetrains for Class 8 trucks, including the Trailer Hybrid Electric (HE) system and the 6X4HE hybrid axle.

In 2018, Hyliion relocated to Cedar Park, Texas, following approval of an economic incentives package from the Cedar Park City Council. During this period, Hyliion acquired Gentherm's battery division.

In 2020, Hyliion merged with Tortoise Acquisition Corp., a special-purpose acquisition company (SPAC). At the time of the merger, the company was valued at US$1.6 billion. In October 2020, activist short-seller Bonitas Research published a critical report in which it disputed Hyliion's claim that its hybrid retrofit system delivered up to 30% fuel efficiency improvements and asserted that only a portion of the customers listed in Hyliion's investor presentations had actually purchased its Hybrid-X system.

In August 2022, Hyliion acquired KARNO generator technology from GE Additive for $37 million.

In November 2023, Hyliion shifted its focus to the KARNO generator. As part of this transition, Hyliion discontinued its powertrain business and reduced its workforce by two-thirds.

In January 2025, Hyliion installed an M Line additive manufacturing system in the United States from Colibrium Additive for production support.