<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0206</schemaVersion>

    <documentType>3/A</documentType>

    <periodOfReport>2017-10-11</periodOfReport>

    <dateOfOriginalSubmission>2017-10-11</dateOfOriginalSubmission>

    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0001494259</issuerCik>
        <issuerName>CarGurus, Inc.</issuerName>
        <issuerTradingSymbol>CARG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001718646</rptOwnerCik>
            <rptOwnerName>Rothman Simon</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2 CANAL PARK, 4TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CAMBRIDGE</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02141</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Class A Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>100000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeHolding>
            <securityTitle>
                <value>Class B Common Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>200000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Series A Convertible Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F3"/>
            </conversionOrExercisePrice>
            <exerciseDate>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>285684</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each share of Class B Common Stock is convertible into one share of Class A Common Stock at the option of the reporting person or automatically either upon the transfer of such share of Class B Common Stock, except for certain transfers described in the Issuer's amended and restated certificate of incorporation, or upon the date falling after the first to occur of the death of Langley Steinert, Langley Steinert's voluntary termination of all employment with the Issuer and service on the Issuer's board of directors or the sum of the number of shares of the Issuer's capital stock held by Langley Steinert, by any Family Member of Langley Steinert, and by any Permitted Entity of Langley Steinert</footnote>
        <footnote id="F2">(as such terms are defined in the Issuer's amended and restated certificate of incorporation), assuming the exercise and settlement in full of all outstanding options and convertible securities and calculated on an as-converted to Class A Common Stock basis, being less than 9,091,484 shares.</footnote>
        <footnote id="F3">At any time at the holder's election, each share of the Issuer's Series A convertible preferred stock (the &quot;Series A Preferred&quot;) is convertible into shares of the Issuer's common stock, one third of which number of shares shall be Class A Common Stock and two thirds of which number of shares shall be Class B Common Stock, on a 6.0000023-for-one basis without payment or consideration. Upon the closing of the Issuer's initial public offering of its Class A Common Stock, each share of the Series A Preferred will automatically convert into shares of the Issuer's Class A Common Stock on a 6.0000023-for-one basis without payment or consideration. The Series A Preferred has no expiration date.</footnote>
    </footnotes>

    <remarks>The holdings reported on this amended filing were previously reported on the Form 3 filed by the reporting person on October 11, 2017 and have been included in this amendment for reference only.  This amended filing is being made solely to amend footnotes 1 and 2.</remarks>

    <ownerSignature>
        <signatureName>/s/ Kathleen Patton, as attorney-in-fact</signatureName>
        <signatureDate>2017-10-18</signatureDate>
    </ownerSignature>
</ownershipDocument>
