<SEC-DOCUMENT>0001467858-18-000005.txt : 20180103
<SEC-HEADER>0001467858-18-000005.hdr.sgml : 20180103
<ACCEPTANCE-DATETIME>20180103183952
ACCESSION NUMBER:		0001467858-18-000005
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20171231
FILED AS OF DATE:		20180103
DATE AS OF CHANGE:		20180103

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Stephenson Carol
		CENTRAL INDEX KEY:			0001493255

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34960
		FILM NUMBER:		18507578

	MAIL ADDRESS:	
		STREET 1:		300 RENAISSANCE CENTER
		STREET 2:		M/C:482-C25-A36
		CITY:			DETROIT
		STATE:			MI
		ZIP:			48265-3000

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			General Motors Co
		CENTRAL INDEX KEY:			0001467858
		STANDARD INDUSTRIAL CLASSIFICATION:	MOTOR VEHICLES & PASSENGER CAR BODIES [3711]
		IRS NUMBER:				270756180
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		300 RENAISSANCE CENTER
		CITY:			DETROIT
		STATE:			MI
		ZIP:			48265-3000
		BUSINESS PHONE:		313.667.1500

	MAIL ADDRESS:	
		STREET 1:		300 RENAISSANCE CENTER
		CITY:			DETROIT
		STATE:			MI
		ZIP:			48265-3000
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_151502277788375.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-12-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001467858</issuerCik>
        <issuerName>General Motors Co</issuerName>
        <issuerTradingSymbol>GM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001493255</rptOwnerCik>
            <rptOwnerName>Stephenson Carol</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>300 RENAISSANCE CENTER</rptOwnerStreet1>
            <rptOwnerStreet2>M/C: 482-C23-D24</rptOwnerStreet2>
            <rptOwnerCity>DETROIT</rptOwnerCity>
            <rptOwnerState>MI</rptOwnerState>
            <rptOwnerZipCode>48265-3000</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Deferred Share Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.0</value>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-12-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5950</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>5950.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>49157</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Deferred Share Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.0</value>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-12-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1936</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>1936.0</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>51093</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Deferred share units of the Company's Common Stock (&quot;DSUs&quot;) were awarded on December 31, 2017 pursuant to the General Motors Company Deferred Compensation Plan (the &quot;Plan&quot;) for Non-Employee Directors. Each non-employee director is required to defer one-half of the $285,000 annual retainer fee for service on the Board of Directors into DSUs and may elect to defer more. The retainer fee is converted to DSUs based on the average closing price of the Common Stock for the previous calendar year, which was $37.61. Amounts credited as DSUs will be paid in cash after the director leaves the Board, valued at the average daily closing price of the Common Stock for the quarter immediately preceding payment.</footnote>
        <footnote id="F2">Pursuant to the Plan, dividends on the DSUs are credited in DSUs at the end of year.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Tia Y. Turk, Attorney-In-Fact for Ms. Stephenson</signatureName>
        <signatureDate>2018-01-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
