Statement of Changes in Beneficial Ownership (4)

FORM 4

[X] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES

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3235-0287

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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * TortoiseEcofin Borrower LLC	2. Issuer Name and Ticker or Trading Symbol Hyliion Holdings Corp. [ HYLN ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director                    __X__ 10% Owner _____ Officer (give title below)    _____ Other (specify below)
(Last)          (First)          (Middle) 5100 W. 115TH PLACE	3. Date of Earliest Transaction (MM/DD/YYYY) 10/1/2020
(Street) LEAWOOD,, KS 66211 (City)        (State)        (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) ___ Form filed by One Reporting Person _ X _ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. Code (Instr. 8)		4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	10/1/2020		J(1)		894375	A	(1)	5333980	D (2)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Class B Common Stock	(3)	10/1/2020		J (3)		894375		(4)	(4)	Class A Common Stock	894375	(3)	894375	D (2)
Class B Common Stock	(1)	10/1/2020		C			894375	(4)	(4)	Class A Common Stock	894375	(1)	0	D (2)

Explanation of Responses:
(1)	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.
(2)	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.
(3)	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.
(4)	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.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
TortoiseEcofin Borrower LLC 5100 W. 115TH PLACE LEAWOOD,, KS 66211		X
TortoiseEcofin Investments, LLC 5100 W. 115TH PLACE LEAWOOD,, KS 66211		X

Signatures
/s/ TortoiseEcofin Borrower LLC, by Vincent T. Cubbage as Attorney-in-Fact		10/5/2020
**Signature of Reporting Person		Date
/s/ TortoiseEcofin Investments, LLC, by Vincent T. Cubbage as Attorney-in-Fact		10/5/2020
**Signature of Reporting Person		Date