<PAGE>
                                                                   EXHIBIT 10.10



                          AMENDED AND RESTATED GUARANTY

     This Amended and Restated Guaranty ("Guaranty") is made as of the 30th day
of November, 2001 by CCC Information Services Group Inc., a Delaware corporation
(the "Guarantor"), in favor of LaSalle Bank National Association as
representative of and in its capacity as Administrative Agent for the Lenders
and Issuing Bank under the Credit Agreement referred to below (the
"Administrative Agent").

     WHEREAS, CCC Information Services Inc., a Delaware corporation (the
"Borrower"), entered into that certain Amended and Restated Credit Facility
Agreement with certain lenders party thereto (the "Original Lenders") and the
Administrative Agent dated as of October 29, 1998 (as heretofore amended,
restated or otherwise modified, the "Original Credit Agreement"), pursuant to
which the Original Lenders made certain loans and other financial accommodations
available to the Borrower from time to time;

     WHEREAS, in connection with the Original Credit Agreement, the Guarantor
executed that certain Guaranty of CCC Information Services Group Inc., dated
October 29, 1998 in favor of the Administrative Agent (as heretofore amended,
restated or otherwise modified, the "Original Guaranty");

     WHEREAS, the Borrower, the Administrative Agent and certain financial
institutions party to the Original Credit Agreement (the "Lenders") desire to
amend and restate the Original Credit Agreement and enter into the Second
Amended and Restated Credit Facility Agreement (as amended, restated or
otherwise modified from time to time, the "Credit Agreement"; capitalized terms
used herein without definition shall have the meanings given such terms in the
Credit Agreement), pursuant to which the Lenders have agreed to make certain
loans and other financial accommodations available to the Borrower from time to
time;

     WHEREAS, the Guarantor will directly benefit from the loans and other
financial accommodations made available by the Lenders to Borrower; and

     WHEREAS, the Lenders have required, as a condition, among others, to
entering into the Credit Agreement, that the Original Guaranty be amended and
restated hereby and that the Guarantor execute and deliver this Guaranty to
Administrative Agent.

     In consideration of the foregoing, the Guarantor and Administrative Agent
agree as follows:

1.   Guaranty.

     (a) The Guarantor unconditionally guarantees as primary obligor the full
and prompt payment and performance, when due, whether upon demand or otherwise,
and at all times thereafter of all of the obligations of Borrower to the
Lenders, the Issuing Bank and the Administrative Agent (collectively, the
"Obligees") under and in connection with the Credit



<PAGE>

Agreement, any and all notes issued by the Borrower thereunder and under any
agreement executed in connection therewith, including but not limited to, with
respect to any Letter of Credit issued thereunder (all such obligations
collectively referred to herein as the "Obligations"). The Guarantor hereby
agrees that this Guaranty is an absolute guarantee of payment and performance
and is not a guaranty of collection.

     (b) Notwithstanding anything contained herein to the contrary, the
Guarantor's liability with respect to the payment of the Obligations shall
include all fees, costs and expenses (including, without limitation, all court
costs and outside attorneys' fees and the allocated cost of inhouse attorneys'
and paralegals' fees, costs and expenses) paid or incurred by the Obligees in:
(A) endeavoring to collect all or any part of the Obligations from, or in
prosecuting any action against, the Guarantor; (B) taking any action with
respect to any security or collateral securing the obligations of the Guarantor
under this Guaranty; and (C) preserving, protecting or defending the
enforceability of this Guaranty or its rights hereunder (all such costs and
expenses are referred to hereinafter collectively as the "Expenses").

2.   Payment of Obligations. At any time, and from time to time, if an Event of
Default shall occur and be continuing, the Guarantor shall pay to the
Administrative Agent (for the benefit of the Obligees) on demand and in
immediately available funds, all Obligations then due, whether by acceleration,
maturity or otherwise, together with all Expenses.

3.   Obligations Unconditional.

     (a)  The Guarantor hereby agrees that its obligations under this Guaranty
shall be unconditional, irrespective of:

          (i) the validity or enforceability, avoidance or subordination of any
     of the Obligations;

          (ii) the absence of any attempt by, or on behalf of, the Obligees to
     collect, or take any other action to enforce, all or any part of the
     Obligations from Borrower or from any other guarantor of all or any part or
     the Obligations or any other person;

          (iii) the election of any remedy by, or on behalf of, the Obligees
     with respect to all or any part of the Obligations;

          (iv) the waiver, consent, extension, forbearance or granting of any
     indulgence by, or on behalf of, the Obligees with respect to any provision
     of the Credit Agreement, any notes issued thereunder, the Pledge Agreement,
     or any other instrument or agreement delivered pursuant to or in connection
     with the foregoing other than this Guaranty (collectively, the
     "Documents").

          (v) the failure of the Administrative Agent to take any steps to
     perfect and maintain its security interest in, or to preserve its
     respective right to, any of the collateral for all or any part of the
     Obligations;



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<PAGE>


          (vi) the election by, or on behalf of, the Obligees, in any proceeding
     instituted under the United States Bankruptcy Code (the "Bankruptcy Code")
     of the application of Section 1111(b)(2) of the Bankruptcy Code;

          (vii) any borrowing or grant of a security interest by Borrower, as
     debtor-in-possession, under Section 364 of the Bankruptcy Code;

          (viii) the disallowance under Section 502 of the Bankruptcy Code of
     all or any portion of the claims of the Obligees for repayment of all or
     any part of the Obligations or any Expenses relating thereto; or

          (ix) any other circumstance other than payment in full which might
     otherwise constitute a legal or equitable discharge or defense of a
     guarantor or any Borrower.

     (b)  The Guarantor hereby waives any requirement of diligence, presentment,
demand of payment, filing of claims with a court in the event of receivership or
bankruptcy of Borrower, protest or notice with respect to all or any part of the
Obligations, the benefit of any statutes of limitation, and all demands
whatsoever (and Guarantor shall not require that the same be made on the
Borrower as a condition precedent to any of Guarantor's obligations hereunder),
and covenants that this Guaranty will not be discharged, except by complete
performance of the Obligations or by payment to the Administrative Agent of the
entire amount of the Guarantor's liability hereunder.

4.   Demand, Reinstatement. Upon the occurrence of any Event of Default and as
long as such Event of Default continues, the Administrative Agent may proceed
directly and at once, without further notice, against the Guarantor to obtain
performance of and to collect and recover the full amount, or any portion, of
the Obligations without Administrative Agent first proceeding against the
Borrower, or any other person, or any security or collateral for all or any part
thereof. Payments and credits, if any, from Guarantor, the Borrower, any other
guarantor of all or any portion of the Obligations or any other person on
account of the Obligations or of any other liability or obligation of Guarantor
to the Obligees, shall be applied to the Obligations, and neither Guarantor, nor
the Borrower, nor any other guarantor of all or any portion of the Obligations
nor any other person shall have any further liability with respect to any such
payments and credits if such payments and credits have been made as provided
herein; provided, however, that if such payments or credits, or any part
thereof, are subsequently invalidated, declared to be fraudulent or
preferential, set aside and/or required to be repaid to the Guarantor, the
Borrower, any other guarantor or any other person, or their respective estates,
trustees, receivers or any other party under any bankruptcy law, state or
federal law, common law or equitable cause, then, to the extent of such payment
or repayment, the Obligations or other obligations or liabilities or any part
thereof which has been paid, reduced or satisfied by such amount shall be
reinstated and shall continue in full force and effect as of the time
immediately preceding the time such initial payment, credit, reduction or
satisfaction occurred.

5.   Inability to Collect. The Guarantor agrees that, notwithstanding anything
set forth in this Guaranty to the contrary, if for whatever reason, the
Administrative Agent is prevented by applicable law from exercising any of its
rights to demand payment from the Borrower of all or any part of the
Obligations, to collect interest on all or any part of the Obligations or to
enforce



                                       3
<PAGE>

or exercise any other right or remedy with respect to all or any part of the
Obligations, or is prevented from taking any action to realize on all or any
part of the collateral securing the Obligations or the liabilities of any
guarantor of the Obligations, the Guarantor shall pay to the Administrative
Agent, on demand therefor and in immediately available funds, the amount that
would otherwise have been due and payable had such rights and remedies been
permitted to be exercised by the Administrative Agent.

6.   The Obligees' Actions.

     (a) The Obligees are hereby authorized, without notice or demand and
without affecting the liability of the Guarantor hereunder, from time to time
(i) to renew, extend, accelerate or otherwise change the time for payment of, or
other terms relating to, all or any part of the Obligations or to otherwise
modify, amend or change the terms of the Documents; (ii) to accept partial
payments on all or any part of the Obligations; (iii) to take and hold security
or collateral for the payment of all or any part of the Obligations, this
Guaranty, or any other guaranties of all or any part of the Obligations or other
liabilities of the Borrower; (iv) to exchange, enforce, waive and release any
such security or collateral; (v) to release any other guarantor of the
Obligations; and (vi) to settle, release, compromise, collect or otherwise
liquidate all or any part of the Obligations and exchange, enforce, release or
waive any security or collateral for all or any part of the Obligations, and any
of the foregoing may be done in any manner, without affecting or impairing all
or any part of the obligations of the Guarantor hereunder.

     (b) Subject to the provisions of the Documents, at any time after all or
any part of the Obligations have become due and payable, until all of such
Obligations which are due have been paid, the Administrative Agent may, in its
sole discretion, without notice to Guarantor and regardless of the acceptance of
any security or collateral for the payment hereof, appropriate and apply toward
the payment of all or any part of such Obligations (i) any indebtedness due or
to become due from any Obligee to the Guarantor, and (ii) any monies, credits or
other property belonging to the Guarantor, at any time held by or coming into
the possession of any of the Obligees, or any of the Obligees' affiliates,
custodians or nominees.

     (c) The Guarantor hereby assumes responsibility for keeping itself informed
of the financial condition of the Borrower and any and all endorsers and/or
other guarantors of all or any part of the Obligations, and of all other
circumstances bearing upon the risk of nonpayment of the Obligations, or any
part thereof, that diligent inquiry would reveal, and Guarantor hereby agrees
that none of the Obligees have any duty to advise Guarantor of information known
to it regarding such condition or any such circumstances. Guarantor hereby
acknowledges that it has been furnished copies of the Documents and has had the
opportunity to review any documents relating thereto or financial information
relevant thereto. Guarantor further acknowledges and agrees that in the event
any of the Obligees, in their sole discretion, undertake at any time or from
time to time to provide any such information to Guarantor, then the party
providing such information shall be under no obligation (i) to undertake any
investigation not a part of its regular business routine; (ii) to disclose any
information which, pursuant to accepted or reasonable banking or commercial
finance practices, such party wishes to maintain confidential; or (iii) to make
any other or future disclosures of such information or any other information to
Guarantor.



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<PAGE>

     (d) The Guarantor consents and agrees that the Administrative Agent, or any
person acting for or on behalf of the Obligees, shall not be under any
obligation to marshal any assets in favor of Guarantor or against or in payment
of all or any part of the Obligations.

7.   Waiver of Subrogation and Other Matters.

     (a) Until the Obligations shall have been paid in full, the Guarantor shall
have no right of subrogation and hereby waives any right to enforce any remedy
which the Obligees now have or may hereafter have against the Borrower, any
endorser or any other guarantor of all or any part of the Obligations, and the
Guarantor hereby waives any benefit of, and any right to participate in, any
security or collateral given to the Obligees to secure payment of the
Obligations or any other liability of the Borrower to the Obligees.

     (b) The Guarantor further agrees that any and all claims of the Guarantor
against the Borrower, any endorser or any other guarantor of all or any part of
the Obligations, or against any of their respective properties, whether arising
by reason of any payment by Guarantor pursuant to the provisions hereof, or
otherwise, and all indebtedness of the Borrower to Guarantor, shall be
subordinate and subject in right of payment to the prior payment, in full, of
all principal and interest, all reasonable costs of collection (including,
without limitation, attorneys' and paralegals' fees, costs and expenses) of such
principal and interest and all Obligations owing to the Obligees by the
Borrower. Guarantor also waives all setoffs and counterclaims and all
presentments, demands for performance, notices of nonperformance, protests,
notices of protest, notices of dishonor, and notices of acceptance of this
Guaranty by any person who is at any time an obligee with respect to any of the
Obligations. The Guarantor further waives all notices of the existence, creation
or incurring of new or additional indebtedness, arising either from additional
loans extended to the Borrower or otherwise, and also waives all notices that
the principal amount, or any portion thereof, and/or any interest with respect
to any of the Obligations is due, notices of any and all proceedings to collect
from the maker, any endorser, any other guarantor, or any other person of all or
any part of the Obligations, and, to the extent permitted by law, notices of
exchange, sale, surrender or other handling of any security or collateral given
to, or for the benefit of, the Obligees to secure payment of all or any part of
the Obligations.

     (c) No delay on the part of the Administrative Agent in the exercise of any
right or remedy arising under this Guaranty, or any of the Documents, or
otherwise with respect to all or any part of the Obligations, any collateral
securing the Obligations or any other guaranty of or security for all or any
part of the Obligations shall operate as a waiver thereof, and no single or
partial exercise by any such person of any such right or remedy shall preclude
any further exercise thereof. No modification or waiver of any of the provisions
of this Guaranty shall be binding upon the Obligees except as expressly set
forth in a writing duly executed and delivered by the Obligees. Failure by the
Obligees at any time or times hereafter to require strict performance by the
Borrower, the Guarantor, any other guarantor of all or any part of the
Obligations or any other person of any of the provisions, warranties, terms and
conditions or contained in the Documents shall not waive, affect or diminish any
right of the Obligees at any time or times hereafter to demand strict
performance thereof, and such right shall not be deemed to have been modified or
waived by any act or knowledge of the Obligees, unless such waiver is contained
in an instrument in writing, and directed and delivered to the Guarantor,
specifying



                                       5
<PAGE>

such waiver signed by the Administrative Agent. No waiver by the Obligees of any
default under any of the Documents shall operate as a waiver of any other
default or the same default on a future occasion. Any final determination by a
court of competent jurisdiction of the amount of any principal and/or interest
owing by the Borrower to the Obligees, shall be conclusive and binding on the
Guarantor irrespective of whether the Guarantor was party to the suit or action
in which such determination was made.

     (d) This Guaranty shall continue in full force and effect and may not be
terminated or otherwise revoked until the Obligations shall have been fully
discharged and all of the Commitments under the Credit Agreement have been
terminated.

     (e) This Guaranty shall be binding upon the Guarantor and upon its
successors and assigns of Guarantor and shall inure to the benefit of the
Obligees and their respective successors and assigns. All references herein to
the Borrower or the Guarantor shall be deemed to include their respective
successors and assigns. The successors and assigns of the Borrower and Guarantor
shall include, without limitation, a receiver, trustee or debtor-in-possession
of or for any such party. All references to the singular shall be deemed to
include the plural where the context so requires.

8.   Agency. Pursuant to the Credit Agreement, (a) this Guaranty has been
delivered to the Administrative Agent and (b) the Administrative Agent has been
authorized to enforce this Guaranty on behalf of itself and each of the Lenders.
All payments by the Guarantor pursuant to this Guaranty shall be made to the
Administrative Agent for the benefit of the Lenders.

9.   Choice of Law, Jurisdiction, and Venue. THIS GUARANTY SHALL BE GOVERNED BY
AND CONSTRUED IN ACCORDANCE WITH THE LAW OF THE STATE OF ILLINOIS APPLICABLE TO
CONTRACTS MADE AND TO BE FULLY PERFORMED IN SUCH STATE (INCLUDING, WITHOUT
LIMITATION, 735 ILLINOIS COMPILED STATUES ss.105/5-5). WHEREVER POSSIBLE, EACH
PROVISION OF THIS GUARANTY SHALL BE INTERPRETED IN SUCH MANNER AS TO BE
EFFECTIVE AND VALID UNDER APPLICABLE LAW, BUT IF ANY PROVISION OF THIS GUARANTY
SHALL BE PROHIBITED BY OR INVALID UNDER SUCH LAW, SUCH PROVISION SHALL BE
INEFFECTIVE TO THE EXTENT OF SUCH PROHIBITION OR INVALIDITY, WITHOUT
INVALIDATING THE REMAINDER OF SUCH PROVISION OR THE REMAINING PROVISIONS OF THIS
GUARANTY.

         IN ANY ACTION OR PROCEEDING ARISING UNDER OR RELATING TO THIS GUARANTY,
THE CREDIT AGREEMENT, THE PLEDGE AGREEMENT, OR ANY OF THE OBLIGATIONS (AS
DEFINED HEREIN), THE GUARANTOR HEREBY IRREVOCABLY (A) CONSENTS AND SUBMITS TO
THE EXCLUSIVE JURISDICTION OF ANY STATE OR FEDERAL COURT SITTING IN CHICAGO,
ILLINOIS AND (B) WAIVES ANY OBJECTION WHICH THE GUARANTOR MAY HAVE AT ANY TIME
TO THE LAYING OF VENUE OF ANY SUCH PROCEEDINGS BROUGHT IN ANY SUCH COURT, AND
(C) WAIVES ANY CLAIM THAT SUCH PROCEEDINGS HAVE BEEN BROUGHT IN AN INCONVENIENT
FORUM AND (D) FURTHER WAIVE THE RIGHT TO OBJECT WITH RESPECT TO SUCH
PROCEEDINGS, THAT SUCH COURT DOES NOT HAVE ANY JURISDICTION OVER SUCH PARTY.
THIS FORUM SELECTION



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<PAGE>

AGREEMENT APPLIES NO MATTER WHAT THE FORM OF ACTION, WHETHER IN REM, IN
PERSONAM, OR ANY OTHER, OR WHETHER BASED ON ANY STATUTE, RULE, OR REGULATION,
NOW EXISTING OR HEREAFTER ENACTED.

     THE GUARANTOR HEREBY WAIVES PERSONAL SERVICE OF ANY AND ALL PROCESS UPON IT
AND CONSENTS THAT ALL SUCH SERVICE OF PROCESS MAY BE MADE AT THE OPTION OF THE
ADMINISTRATIVE AGENT BY ANY ONE OF THE FOLLOWING (A) DELIVERY IN PERSON, OR (B)
BY COURIER, OR (C) CERTIFIED OR REGISTERED MAIL, POSTAGE PREPAID, TO THE
GUARANTOR AT ITS ADDRESS NOTED ABOVE, OR (D) BY SERVICE UPON ANY ONE OF THE
FOLLOWING: (1) ITS REGISTERED AGENT, IF ANY, IN ILLINOIS, OR (2) CCC INFORMATION
SERVICES INC., AT WORLD TRADE CENTER, 444 MERCHANDISE MART, CHICAGO, ILLINOIS
60654, WHICH GUARANTOR IRREVOCABLY APPOINTS AS ITS AGENTS FOR THE PURPOSE OF
ACCEPTING SERVICE OF PROCESS FOR ANY ACTION NOT ONLY WITHIN THE STATE OF
ILLINOIS, BUT ALSO ANY OTHER JURISDICTION.

     ANY PROCESS SERVED BY MAIL SHALL BE COMPLETE ON THE DATE IT IS MAILED. ANY
PROCESS SERVED BY ANY OTHER MANNER AFOREMENTIONED SHALL BE COMPLETE ON THE DATE
IT IS DELIVERED. THE GUARANTOR CONSENTS TO SERVICE OF PROCESS AS AFORESAID. THE
GUARANTOR ALSO WAIVES ANY DEFECT IN SERVICE CAUSED BY ITS FAILURE TO NOTIFY THE
ADMINISTRATIVE AGENT IN WRITING OF ANY CHANGE OF ADDRESS.

     IN ADDITION, THE ADMINISTRATIVE AGENT AGREES TO PROMPTLY FORWARD BY
REGISTERED MAIL A COPY OF ANY PROCESS SO SERVED UPON SAID AGENT TO GUARANTOR AT
ITS ADDRESS SET FORTH ABOVE, AND THE GUARANTOR HEREBY CONSENTS TO SERVICE OF
PROCESS AS AFORESAID. GUARANTOR ALSO WAIVES ANY DEFECT IN SERVICE CAUSED BY ITS
FAILURE TO NOTIFY THE ADMINISTRATIVE AGENT IN WRITING OF ANY CHANGE OF ADDRESS.

     NOTHING HEREIN SHALL AFFECT THE RIGHT OF OBLIGEES TO SERVE LEGAL PROCESS IN
ANY OTHER MANNER PERMITTED BY LAW OR THE RIGHT OF THE OBLIGEES TO BRING ANY
ACTION OR PROCEEDING AGAINST THE GUARANTOR OR ITS PROPERTY IN THE COURTS OF ANY
OTHER JURISDICTION.

10.  WAIVER OF JURY TRIAL. BOTH THE GUARANTOR AND THE  ADMINISTRATIVE  AGENT
HEREBY IRREVOCABLY WAIVE TRIAL BY JURY IN ANY ACTION OR PROCEEDING WITH RESPECT
TO THIS GUARANTY.

11.  Severability. Wherever possible, each provision of this Guaranty shall be
interpreted in such manner as to be effective and valid under applicable law,
but if any provision of this Guaranty shall be prohibited by or invalid under
such law, such provision shall be ineffective to the extent of such prohibition
or invalidity without invalidating the remainder of such provision or the
remaining provisions of this Guaranty.



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<PAGE>

12.  Notices. Any notice required or desired to be served, given or delivered
hereunder shall be in writing, and shall be deemed to have been validly served,
given or delivered (i) four (4) Business Days after deposit in the United States
mails by prepaid registered mail or certified United States mail (return receipt
requested), with proper postage prepaid, (ii) when properly transmitted if sent
by telecopy with receipt confirmed, (iii) two (1) Business Days after being
deposited with a reputable overnight courier with all charges prepaid, or (iv)
when delivered, if hand-delivered, by messenger, all of which shall be properly
addressed to the party to be notified and sent to the addresses set forth below
their names on the signature page hereto or to such other address as the parties
shall, from time to time, designate in writing.

13.  Counterparts. This Guaranty may be executed in any number of counterparts,
all of which taken together shall constitute one agreement, and any of the
parties hereto may execute this Guaranty by signing any such counterpart.

14.  References to Original Guaranty. This Guaranty shall become effective, and
shall amend and restate the Original Guaranty upon the execution of this
Guaranty by the parties signatory hereto as of the date hereof (the "Effective
Date"); and from and after the Effective Date, (i) all references made to the
Original Guaranty in the Loan Documents or in any other instrument or document
shall, without more, be deemed to refer to this Guaranty, as may hereafter be
amended, restated or otherwise modified, and (ii) the Original Guaranty shall be
deemed amended and restated in its entirety hereby.

                             SIGNATURE PAGE FOLLOWS



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<PAGE>

     IN WITNESS WHEREOF, this Amended and Restated Guaranty has been duly
executed as of the day and year first set forth above.

                                       CCC INFORMATION SERVICES GROUP INC.

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

                                       Notice Address:

                                       c/o CCC Information Services Inc.
                                       World Trade Center Chicago
                                       444 Merchandise Mart
                                       Chicago, Illinois  60654
                                       Attention:
                                       Facsimile: (312) 527-1494

                                       LASALLE BANK NATIONAL ASSOCATION

                                       By:  /s/ Aimee W. Daniels
                                           ------------------------------------
                                            Title: Sr. Vice President

                                       Notice Address:

                                       LaSalle Bank National
                                       Association 135 South
                                       LaSalle Street Chicago,
                                       Illinois 60603
                                       Attention:

                                       Facsimile: (312) 904-0409





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