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                                                                    EXHIBIT 10.5

                       CCC INFORMATION SERVICES GROUP INC.
                           WORLD TRADE CENTER CHICAGO
                              444 MERCHANDISE MART
                             CHICAGO, ILLINOIS 60654


                                November 30, 2001

TO:      Capricorn Investors III, L.P. ("Capricorn")
         30 East Elm Street
         Greenwich, Connecticut 06830

Gentlemen:

         Reference is made to (a) the Purchase Agreement, dated as of November
29, 2001 (the "Purchase Agreement"), by and among CCC Information Services Group
Inc. (the "Company"), White River Ventures, Inc. ("White River"), Capricorn
Investors II, L.P. ("Capricorn II") and Capricorn, and the transactions
contemplated therein, relating to the purchase by White River, Capricorn II and
Capricorn of shares of the Company's common stock, par value $0.10 per share
(the "Common Stock") pursuant to the Pro Rata Exercise and the Standby
Commitment and (b) that certain Side Letter, dated February 23, 2001, between
the Company and Capricorn (the "February Side Letter") relating to, among other
things, (i) the sale by CCC Capital Trust (the "Trust") to Capricorn of 15,000
trust preferred securities of the Trust (liquidation amount of $1,000 per trust
preferred security), representing undivided beneficial interests in the assets
of the Trust (the "Trust Preferred Securities") and (ii) the sale by the Company
to Capricorn of a warrant (the "Warrant") to purchase 1,200,000 shares of Common
Stock. Terms used herein without definition shall have the meaning assigned to
such terms in the Purchase Agreement or the February Side Letter, as applicable.

         In consideration of the Rights Offering and the transactions
contemplated by the Purchase Agreement and the amendment of the Warrant in
connection therewith, Capricorn hereby agrees as follows:

         1. Notwithstanding the other provisions of the February Side Letter,
Capricorn hereby waives any rights it may have pursuant to paragraph 2 of the
February Side Letter to pay the Subscription Price per share of Common Stock
purchased pursuant to its Pro Rata Exercise and pursuant to its obligations
under the Standby Commitment through the surrender or exchange of the Securities
(as defined in the February Side Letter), and confirms that such Subscription
Price shall be paid in the manner provided in the Purchase Agreement.

         2. The Company and Capricorn hereby agree that (i) the Rights Offering
and the transactions contemplated by the Purchase Agreement shall constitute the
alternative financing as contemplated in Paragraph 2 of the February Side Letter
and (ii) the February Side Letter shall


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terminate in all respects, and any rights of Capricorn, or obligations of the
Company to Capricorn, thereunder shall be of no further force or effect, upon
the Initial Closing Date.

         3. This letter agreement shall be effective, as against any party,
after execution and delivery of a counterpart signature hereof by such party.

         4. This letter agreement shall not be assignable by the Company or
Capricorn (other than to a successor-in-interest of such party) without the
prior written consent of the other party hereto (and any purported assignment
without such consent shall be null and void), is intended to be solely for the
benefit of the parties hereto and is not intended to confer any benefits upon,
or create any rights in favor of, any person other that the parties hereto and
their permitted successors and assigns. No terms of this letter agreement may be
amended or waived except by an instrument in writing signed by the party against
whom such amendment or waiver is sought to be enforced. This letter agreement
may be executed in any number of counterparts, each of which shall be an
original, and all of which, when taken together, shall constitute one agreement.
Delivery of an executed signature page of this letter agreement by facsimile
transmission shall be as effective as delivery of a manually executed
counterpart hereof. This letter agreement shall be governed by, and construed in
accordance with, the laws of the State of Delaware, without giving effect to its
principles of conflicts of law.


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                                    Very truly yours,

                                    CCC INFORMATION SERVICES GROUP INC.


                                    By: /s/ Reid E. Simpson
                                        ----------------------------------------
                                    Name:    Reid E. Simpson
                                    Title:   Executive Vice President
                                             and Chief Financial Officer


Accepted and agreed:

CAPRICORN INVESTORS III, L.P.

By: CAPRICORN HOLDINGS III, LLC,
    its General Partner


By: /s/ Herbert S. Winokur, Jr.
        -------------------------------------
Name:   Herbert S. Winokur, Jr.
Title:  Manager