X0306 4 2020-10-01 1 0001759631 Hyliion Holdings Corp. HYLN 0001735321 TortoiseEcofin Borrower LLC 5100 W. 115TH PLACE LEAWOOD, KS 66211 0 0 1 0 0001730884 TortoiseEcofin Investments, LLC 5100 W. 115TH PLACE LEAWOOD, KS 66211 0 0 1 0 Common Stock 2020-10-01 4 J 0 894375 A 5333980 D Class B Common Stock 2020-10-01 4 J 0 894375 A Class A Common Stock 894375 894375 D Class B Common Stock 2020-10-01 4 C 0 894375 D Class A Common Stock 894375 0 D In connection with the closing of the business combination between Tortoise Acquisition Corp. ("TortoiseCorp"), SHLL Merger Sub Inc. and Hyliion Inc. on October 1, 2020, the Reporting Person's shares of Class B Common Stock automatically converted into shares of TortoiseCorp's Class A Common Stock on a one-for-one basis. Upon consummation of the business combination, TortoiseCorp changed its name to "Hyliion Holdings Corp." and all outstanding shares of Class A Common Stock were automatically reclassified, redesignated and changed into one share of Hyliion Holdings Corp. Common Stock. TortoiseEcofin Borrower LLC is the record holder of the shares reported herein. TortoiseEcofin Parent Holdco LLC is the sole member of TortoiseEcofin Borrower LLC, and TortoiseEcofin Investments, LLC is the sole member of TortoiseEcofin Parent Holdco LLC. Accordingly, TortoiseEcofin Investments, LLC may be deemed to have or share beneficial ownership of the shares of Class B Common Stock held directly by TortoiseEcofin Borrower LLC. The address of each of TortoiseEcofin Borrower LLC and TortoiseEcofin Investments, LLC is 5100 W. 115th Place, Leawood, Kansas 66211. In connection with the closing of the business combination between TortoiseCorp, SHLL Merger Sub Inc. and Hyliion Inc. on October 1, 2020, Atlas Point Energy Infrastructure Fund, LLC ("Atlas Point Fund") transferred 894,375 shares of Class B Common Stock to the Reporting Person, pursuant to the Amended and Restated Forward Purchase Agreement, dated February 6, 2019, by and among TortoiseCorp, Tortoise Sponsor LLC and Atlas Point Fund, as amended by the First Amendment to Amended and Restated Forward Purchase Agreement, dated as of June 18, 2020. The shares of Class B Common Stock are automatically convertible into shares of Class A Common Stock at the time of TortoiseCorp's initial business combination on a one-for-one basis, subject to adjustment pursuant to certain anti-dilution rights, and have no expiration date. /s/ TortoiseEcofin Borrower LLC, by Vincent T. Cubbage as Attorney-in-Fact 2020-10-05 /s/ TortoiseEcofin Investments, LLC, by Vincent T. Cubbage as Attorney-in-Fact 2020-10-05