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

    <schemaVersion>X0206</schemaVersion>

    <documentType>3</documentType>

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

    <noSecuritiesOwned>0</noSecuritiesOwned>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001719293</rptOwnerCik>
            <rptOwnerName>Parker David Lambert</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>1052136</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Upon the closing of the Issuer's sale of its Class A Common Stock in its firm commitment underwritten initial public offering pursuant to a registration statement on Form S-1 (File No. 333-220495) under the Securities Act of 1933, as amended (the &quot;IPO&quot;), each share of Class B Common Stock will be convertible into one share of Class A Common Stock at the option of the reporting person or automatically 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 effective upon such closing, and upon the date falling after the first to occur of the death of the reporting person'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.</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 IPO, 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>Exhibit 24.1 - Power of Attorney</remarks>

    <ownerSignature>
        <signatureName>/s/ Kathleen Patton, as attorney-in-fact</signatureName>
        <signatureDate>2017-10-11</signatureDate>
    </ownerSignature>
</ownershipDocument>
