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                                                                     EXHIBIT 4.8

                        IDEALAB! STOCKHOLDER AGREEMENT

     This Stockholder Agreement (the "Agreement") is made as of December 30,
1999, by and between Bill Gross' idealab!, Inc., a California corporation
("BGIL"), and idealab! Holdings, L.L.C., a Delaware limited liability company
("idealab!"), on the one hand (BGIL and idealab!, collectively, the "idealab!
Parties"), and CarsDirect.com, Inc., a Delaware corporation, on the other hand
(the "Company").

     A.   The Company and idealab! have entered into a Class B Common Stock
Purchase Agreement (the "Purchase Agreement") pursuant to which idealab! agrees
to purchase from the Company, and Company agrees to sell to idealab!, 2,050,000
shares of the Company's Class B Common Stock, par value $0.001 per share;

     B.   The Company and the idealab! Parties desire, in connection with the
consummation of the transactions contemplated by the Purchase Agreement, to make
certain covenants and agreements with one another pursuant to this Agreement;

     C.   It is a mutual condition to the consummation of the transactions
contemplated by the Purchase Agreement that the idealab! Parties and the Company
enter into this Agreement.

     NOW THEREFORE, in consideration of the covenants and promises set forth
herein, and for other good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, the parties hereby agree as
follows:

                                   ARTICLE I

                                  DEFINITIONS

     For the purpose of this Agreement, the following terms shall have the
meanings specified with respect thereto below:

     "Affiliate" shall have the meaning set forth in Rule 12b-2 of the rules and
regulations promulgated under the Exchange Act; provided, however, that for
purposes of this Agreement, the idealab! Parties and their Affiliates, on the
one hand, and the Company and its Affiliates, on the other hand, shall not be
deemed to be  "Affiliates" of one another.

     "Beneficially Own" or "Beneficial Ownership" shall have the meaning set
forth in Rule 13d-3 of the rules and regulations promulgated under the Exchange
Act.

     "Change in Control of the Company" shall mean any of the following: (i) a
merger, consolidation or other business combination or transaction to which the
Company is a party which results in

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the holders of Class A Common Stock (assuming for purposes of the clause (i)
that all shares of Class B Common Stock have been converted into shares of Class
A Common Stock in accordance with the terms of the Company's Restated
Certificate of Incorporation) of the Company immediately prior to the effective
date of such merger, consolidation or other business combination or transaction,
as a result of such share ownership and such transaction, having Beneficial
Ownership following such merger, consolidation or other business combination or
transaction of voting securities representing less than 50% of the Total Voting
Power of the surviving or resulting corporation (or any parent entity thereof);
(ii) a sale of all or substantially all the assets of the Company; or (iii) a
liquidation or dissolution of the Company.

     "Closing" shall have the meaning set forth in the Purchase Agreement.

     "Company Common Stock" shall mean shares of the Class A Common Stock of the
Company, par value $0.001 per share.

     "Company Notice" shall have the meaning set forth in Section 3.1(a) below.

     "Exchange Act" shall mean the Securities Exchange Act of 1934, as amended.

     "Fair Market Value" shall mean, in the case of New Preferred Stock, the
fair market value as of the date of determination of such New Preferred Stock as
determined in good faith by the members of the Company's Board of Directors that
are not affiliates of the idealab! Parties or the Related Parties.

     "HSR Act" shall mean the Hart-Scott-Rodino Antitrust Improvements Act of
1976, as amended.

     "New Preferred Stock" shall mean shares of a new series of preferred stock
of the Company, par value $0.001 per share, that the Company may designate and
issue from time to time as required under Section 3.1 below and having rights,
preferences, privileges and restrictions substantially similar to those of the
Company's Series D Preferred Stock.

     "New Securities" shall mean Voting Stock issued by the Company after the
date of this Agreement, excluding any such issuance of Voting Stock (i) upon
exercise of stock options to employees, directors and consultants issued from
time to time or upon conversion or exchange of convertible securities
outstanding on the date hereof, (ii) to any idealab! Party or any Affiliate
thereof, (iii) pursuant to the exercise by the idealab! Parties of their rights
pursuant to Section 3.1 below, (iv) to Bank One, N.A. ("Bank One") in connection
with the Company's acquisition of Bank One's ownership interest in CDOne
Financial, (v) of the Company's Series D Preferred Stock authorized as of the
date hereof, and (vi) in connection with strategic transactions of the Company
approved in writing by the Chairman of the Board of Directors of the Company
(with such issuances not to exceed 500,000 shares in the aggregate).

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     "Pro Rata Share" shall mean that number of shares of New Preferred Stock
that solves for "X" according to the following formula: {X/(the number of New
Securities + X)=63%}; provided that, for the avoidance of doubt, the number of
                      --------
New Securities in such formula shall include all shares of Voting Stock issuable
upon the conversion, exchange or exercise of all convertible securities to be
issued at such time.

     "Qualified Initial Public Offering" shall mean a firm commitment
underwritten public offering pursuant to an effective registration statement
under the Securities Act covering the offer and sale of Company Common Stock to
the public involving gross proceeds to the Company not less than $20 million at
a per share price of at least $7.00.

     "Related Party" shall mean any of the following: (i) idealab!, (ii) BGIL,
(iii) any directly or indirectly wholly-owned subsidiary of BGIL (an "idealab!
Sub"), (iv) idealab! Capital Management I LLC ("ICM1"), (v) idealab! Capital
Management II LLC ("ICM2"), and (vi) any venture capital fund in which ICM1 or
ICM2 is a general partner or managing member (an "ICM Fund").  idealab! shall
cease to be a Related Party if and when it is no longer wholly-owned by BGIL.
An idealab! Sub shall cease to be a Related Party if and when it is no longer
wholly-owned (directly or indirectly) by BGIL.  ICM1 shall cease to be a Related
Party if and when neither idealab! nor BGIL serves as its managing member.  ICM2
shall cease to be a Related Party if and when neither idealab! nor BGIL serves
as its managing member.  An ICM Fund shall cease to be a Related Party if and
when (a) neither ICM1 nor ICM2, as the case may be, serves as general partner or
managing member of such ICM Fund, or (b) neither idealab! nor BGIL serves as the
managing member of such general partner or managing member.

     "SEC" shall mean the U.S. Securities and Exchange Commission.

     "Securities Act" shall mean the Securities Act of 1933, as amended.

     "Shares" shall mean any shares of Voting Stock Beneficially Owned by any
idealab! Party, Related Party or any entity controlled by an idealab! Party or
Related Party, after giving effect to the conversion or exchange of or other
exercise of rights to acquire all Voting Stock held by any idealab! Party,
Related Party or any entity controlled by an idealab! Party or Related Party
which is or could be pursuant to its terms convertible, exchangeable or
exercisable into securities of the Company having the power to vote in the
election of members of the Board of Directors of the Company, other than
conversion of shares of Class B Common Stock of the Company into shares of Class
A Common Stock of the Company.

     "Standstill Limit" shall mean 66% of the Total Voting Power.

     "Standstill Period" shall mean the period beginning on the date hereof and
ending on the earliest to occur of the following: (i) the third anniversary of
the Closing or (ii) the consummation of a transaction that results in a Change
in Control of the Company.

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     "Total Voting Power" shall mean, with respect to any entity, the total
number of votes which may be cast in the election of members of the Board of
Directors of the corporation if all securities entitled to vote in the election
of such directors are present and voted.

     "Voting Stock" shall mean shares of the Company Common Stock and any other
securities of the Company having the power to vote, or which are or could be
pursuant to its terms convertible, exchangeable or otherwise exercisable into
securities of the Company having the power to vote, in the election of members
of the Board of Directors of the Company.

     "13D Group" means any group of persons formed for the purpose of acquiring,
holding, voting or disposing of Voting Stock which would be required under
Section 13(d) of the Exchange Act, and the rules and regulations promulgated
thereunder in effect as of the date hereof, to file a statement on Schedule 13D
pursuant to Rule 13d-1(a) or a Schedule 13G pursuant to Rule 13d-1(c) with the
SEC as a "person" within the meaning of Section 13(d)(3) of the Exchange Act if
such group Beneficially Owned Voting Stock representing more than 5% of any
class of Voting Stock then outstanding.

                                  ARTICLE II

              THE PURCHASER'S COVENANTS AND THE COMPANY'S RIGHTS

     2.1  The idealab! Parties' Standstill Obligations
          --------------------------------------------

          (a) Notwithstanding anything to the contrary contained herein and only
during the Standstill Period, the idealab! Parties shall not, nor will the
idealab! Parties permit any entity controlled by any of the idealab! Parties or
any 13D Group of which any of the idealab! Parties is a member to, directly or
indirectly acquire or Beneficially Own Voting Stock, or authorize or make a
tender offer, exchange offer or other offer therefor, if the result of such
acquisition or Beneficial Ownership would be that the percentage of Total Voting
Power represented by all Shares would exceed the Standstill Limit; provided that
                                                                   --------
all shares of Voting Stock Beneficially Owned by ICM1 or ICM2 as of the date
hereof shall not be included in the number of shares Beneficially Owned by the
idealab! Parties for purposes of this Section 2.1.

          (b) During the Standstill Period, the idealab! Parties shall notify
the Company of any acquisition of additional shares of Voting Stock by any
idealab! Party, any entity controlled by any of the idealab! Parties or any 13D
Group of which any of the idealab! Parties is a member promptly after each such
acquisition and in any event not more than five (5) business days thereafter.

          (c) During the Standstill Period, the idealab! Parties shall not, nor
will the idealab! Parties permit any entity controlled by any of the idealab!
Parties to, solicit proxies with respect to any Voting Stock, nor shall it
become a "participant" in any "election contest" (as such terms are used in

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Rule 14(a)-11 of Regulation 14A promulgated under the Exchange Act) relating to
the election of directors of the Company. Nothing in this Section 2.1(c) shall
be construed to limit: (i) the right of any officer or director of the Company
to communicate with any member of the Board of Directors of the Company, any
executive officer of the Company, counsel to the Company or auditors for the
Company, as may be necessary, in such officer's or director's reasonable
judgment, for the discharge of such officer's or director's duties; (ii) the
activities of any officer of the Company to discharge the duties of such office;
or (iii) the right of any stockholder to communicate with any member of the
Board of Directors of the Company.

          (d) During the Standstill Period, the idealab! Parties shall not, nor
will the idealab! Parties permit any entity controlled by any idealab! Party to,
deposit any shares of Voting Stock in a voting trust or subject any Voting Stock
to any arrangement or agreement with any party other than a Related Party with
respect to the voting of such Voting  Stock.

          (e) During the Standstill Period, the idealab! Parties shall not join
a 13D Group, partnership, limited partnership, syndicate or other group, or
otherwise act in concert with any person (other than a Related Party) for the
purpose of acquiring, holding or Voting Stock having Total Voting Power in
excess of the Standstill Limit.

          (f) The restrictions contained in Paragraphs (a) and (e) (solely to
the extent that Paragraph (a) or (e) restricts the activities that are
restricted by Paragraphs (c) or (d)) and (c) and (d) of this Section 2.1 shall
not apply if both (i) the idealab! Parties collectively own shares of Voting
Stock representing less than 50% of the Total Voting Power of the Company and
(ii) (A) a tender offer or exchange offer is made by any person or 13D Group
(other than an Affiliate of, or person acting in concert with, any idealab!
Party and other than a tender offer or exchange offer that is induced by any
idealab! Party or any Affiliate thereof) to acquire shares of Voting Stock
which, if added to the Shares of Voting Stock (if any) already owned by such
person or 13D Group, would represent more than 20% of the Total Voting Power of
the Company at such time, (B) it is publicly disclosed that shares of Voting
Stock representing more than 20% of the Total Voting Power of the Company have
been acquired subsequent to the date hereof, or are proposed to (in a public
announcement or filing) to be acquired subsequent to the date hereof by any
person or 13D Group (other than an Affiliate of, or any person acting in concert
with, any idealab! Party and other than any such acquisition or proposed
acquisition of Voting Stock that has been induced, in whole or in part, by any
idealab! Party or any Affiliate thereof), or (C) any person or 13D Group (not
including any idealab! Party or Affiliates of an idealab! Party) shall
Beneficially Own shares of Voting Stock representing a percentage of the Total
Voting Power of the Company which exceeds the greater of (x) 20% of the Total
Voting Power of the Company or (y) the percentage of the Total Voting Power of
the Company represented by the Shares, and would be required (under rules and
regulations in effect as of the date hereof) to file a statement on Schedule 13D
with the Securities and Exchange Commission reporting beneficial ownership of
such shares of Voting Stock.

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     2.2  The idealab! Parties' Transfer Restrictions.
          -------------------------------------------

          (a) Until the earlier of two (2) years following the date hereof or
eighteen (18) months following a Qualified Initial Public Offering, the idealab!
Parties shall not, and shall not permit any entity controlled by any idealab!
Party to, directly or indirectly, sell, transfer, pledge, contract to sell, sell
any option or contract to purchase, purchase any option or contract to sell,
grant any option, right or warrant to purchase or otherwise dispose of, any
Voting Stock except: (i) to the Company; (ii) to a Related Party, so long as
such Related Party agrees to be bound by the provisions of this Agreement as an
idealab! Party, and agrees to transfer such Voting Stock to an idealab! Party or
another Related Party if and when it ceases to be a Related Party; (iii) in
connection with a Change in Control of the Company approved in accordance with
the Company's Restated Certificate of Incorporation, or (iv) for pledges of
Voting Stock to nationally-recognized financial institutions (not affiliated
with an idealab! Party or a Related Party) as collateral in connection with bona
fide lending transactions.

          (b) Any attempted sale, transfer or other disposition of Voting Stock
which is not in compliance with this Section 2.2 shall be null and void.

                                  ARTICLE III

                 THE COMPANY'S COVENANTS AND IDEALAB!'S RIGHTS

     3.1  idealab!'s Rights to Maintain.  Until the closing of a Qualified
          -----------------------------
Initial Public Offering, idealab! (or, at idealab!'s option, any Related Party)
shall have the right to purchase that number of shares of New Preferred Stock
equal to the Pro Rata Share of any New Securities which the Company may, from
time to time, issue, in accordance with the following terms and conditions:

          (a) In the event the Company proposes to undertake an issuance of New
Securities, it shall give idealab! written notice of its intention (the "Company
Notice"), describing the amount and type of New Securities, and the price and
material terms upon which the Company then proposes to issue the same.  idealab!
shall have ten (10) business days from the date of receipt of the Company Notice
to provide the Company with written notice (the "idealab! Notice") of its
intention to purchase (or its intention to have a Related Party purchase) a
number of shares of New Preferred Stock up to the Pro Rata Share, for a price
equal to the Fair Market Value of such New Preferred Stock as of the date of the
first closing of the issuance of New Securities.  The closing of any such sale
of New Preferred Stock must occur no later than thirty (30) days after the
issuance of the related New Securities, subject to extension as needed for the
parties to comply with the HSR Act with respect to such sale.  The Company
agrees to use reasonable best efforts to secure requisite stockholder approvals
of the authorization and issuance of any New Preferred Stock required pursuant
to this Section 3.1, and failure of the Company to issue New Preferred Stock as
required pursuant to this Section 3.1 shall constitute a material breach of this
Agreement by the Company (whether or not the Company is able to obtain any
requisite stockholder approvals).

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          (b) The provisions of this Section 3.1 will terminate and be of no
further force or effect upon the earlier to occur of: (i) the closing of a
Qualified Initial Public Offering, or (ii) a Change in Control of the Company.

                                  ARTICLE IV

                                 MISCELLANEOUS

     4.1  Governing Law.  This Agreement shall be governed in all respects by
          -------------
the internal laws of the State of California.

     4.2  Successors and Assigns.  This Agreement shall inure to the benefit of,
          ----------------------
and be binding upon, the parties hereto and their respective successors and
assigns.  Except as otherwise provided in this Agreement, this Agreement may not
be assigned by a party without the prior written consent of the other parties
hereto.

     4.3  Entire Agreement; Amendment.  This Agreement constitutes the full and
          ---------------------------
entire understanding and agreement between the parties with regard to the
subject hereof.  Except as expressly provided herein, neither this Agreement nor
any term hereof may be amended, waived, discharged or terminated other than by a
written instrument signed by the party against whom enforcement of any such
amendment, waiver, discharge or termination is sought, including on behalf of
the Company, approval by a majority of the members of the Board of Directors
that are not, and have not for the then previous twelve (12) months been,
Affiliates of any idealab! Party or any Related Party.

     4.5  Notices, etc.  All notices and other communications required or
          ------------
permitted hereunder shall be in writing and shall be mailed by registered or
certified mail, postage prepaid, or otherwise delivered by facsimile
transmission, by hand or by messenger, addressed:

               (a)  If to the idealab! Parties, to:

                    idealab! Holdings, L.L.C.
                    130 West Union Street
                    Pasadena, California 91103
                    Attn: General Counsel
                    (Telephone)  (626) 535-2828
                    (Facsimile)  (626) 535-2703

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With a copy to:

                    Latham & Watkins
                    633 West Fifth Street, Suite 4000
                    Los Angeles, California 90071-2007
                    Attn: David M. Hernand, Esq.
                    (Telephone)  (213) 485-1234
                    (Facsimile)  (213) 891-8763

               (b)  If to the Company, to:

                    CarsDirect.com, Inc.
                    10567 Jefferson Boulevard
                    Culver City, CA 90232
                    Attn: Chief Financial Officer
                          General Counsel
                    (Telephone) (310) 280-4380
                    (Facsimile) (310) 649-5302

With a copy to:

                    Wilson Sonsini Goodrich & Rosati
                    Professional Corporation
                    Two Palo Alto Square
                    Palo Alto, CA 94306
                    Attn:  Martin W. Korman, Esq.
                           Michael D. Weisberg, Esq.
                    (Telephone) (650) 493-9300
                    (Facsimile) (650) 493-6811

     Each such notice or other communication shall for all purposes of this
Agreement be treated as effective or having been given when delivered if
delivered personally, if sent by facsimile, the first business day after the
date of confirmation that the facsimile has been successfully transmitted to the
facsimile number for the party notified, or, if sent by mail, at the earlier of
its receipt or 72 hours after the same has been deposited in a regularly
maintained receptacle for the deposit of the United States mail, addressed and
mailed as aforesaid.

     4.6  Delays or Omissions.  Except as expressly provided herein, no delay or
          -------------------
omission to exercise any right, power or remedy accruing to a party under this
Agreement, shall impair any such right, power or remedy nor shall it be
construed to be a waiver of any such breach or default, or an acquiescence
therein, or of or in any similar breach or default thereafter occurring; nor
shall any waiver

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of any single breach or default be deemed a waiver of any other breach or
default theretofore or thereafter occurring.

     4.7  Expenses.  The Company and the idealab! Parties shall bear their own
          --------
expenses incurred with respect to this Agreement and the transactions
contemplated hereby, provided, that the idealab! Parties shall pay any filing
fee required under the HSR Act arising out of this Agreement or the transactions
contemplated hereby, including any issuances and sales of New Preferred Stock
pursuant to idealab!'s rights to maintain set forth in Section 3.1 above.

     4.8  Specific Performance.  The parties hereto acknowledge and agree that
          --------------------
irreparable damage would occur in the event any of the provisions of this
Agreement were not performed in accordance with their specific terms or were
otherwise breached and that such damage would not be compensable in money
damages and that it would be extremely difficult or impracticable to measure the
resultant damages.  It is accordingly agreed that any party hereto shall be
entitled to an injunction or injunctions to prevent breaches of the provisions
of the Agreement and to enforce specifically the terms and provisions hereof, in
addition to any other remedy to which it may be entitled at law or equity, and
such party that is sued for breach of this Agreement expressly waives any
defense that a remedy in damages would be adequate and expressly waives any
requirement in an action for specific performance for the posting of a bond by
the party bringing such action.

     4.9  Further Assurances.  The parties hereto shall do and perform or cause
          ------------------
to be done and performed all such further acts and things and shall execute and
deliver all such other agreements, certificates, instruments or documents as any
other party may reasonably request from time to time in order to carry out the
intent and purposes of this Agreement and the consummation of the transactions
contemplated hereby.  Neither the Company nor the idealab! Parties shall
voluntarily undertake any course of action inconsistent with satisfaction of the
requirements applicable to them set forth in this Agreement and each shall
promptly do all such acts and take all such measures as may be appropriate to
enable them to perform as early as practicable the obligations herein and
therein required to be performed by them.

     4.10 Counterparts.  This Agreement may be executed in any number of
          ------------
counterparts, each of which may be executed by fewer than all of the parties,
each of which shall be enforceable against the parties actually executing such
counterparts, and all of which together shall constitute one instrument.

     4.11 Severability.  In the event that any provision of .this Agreement
          ------------
becomes or is declared by a court of competent jurisdiction to be illegal,
unenforceable or void, this Agreement shall continue in full force and effect
without said provision; provided, that no such severability shall be effective
if it materially changes the economic impact of this Agreement on any party.

     4.12 Captions.  Headings of the various sections of this Agreement have
          --------
been inserted for convenience of reference only and shall not be relied upon in
construing this Agreement.  Use of any

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gender herein to refer to any person shall be deemed to comprehend masculine,
feminine, and neuter unless the context clearly requires otherwise.

     4.13 Attorneys' Fees.  In any action at law or suit in equity in relation
          ---------------
to this Agreement, the prevailing party in such action or suit shall be entitled
to receive a reasonable sum for its attorneys' fees and all other reasonable
costs and expenses incurred in such action or suit.


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     IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of
the day and year first above written.

                                        "COMPANY"

                                        CARSDIRECT.COM, INC.



                                        By: /s/ Robert N. Brisco
                                           -------------------------------
                                            Name: Robert N. Brisco
                                            Title: CEO


                                        "IDEALAB! PARTIES"

                                        IDEALAB! HOLDINGS, L.L.C.



                                        By: /s/ Bill Gross
                                           -------------------------------
                                            Name:
                                            Title:


                                        BILL GROSS' IDEALAB!, INC.



                                        By: /s/ Bill Gross
                                           -------------------------------
                                            Name:
                                            Title: Chairman

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