<PAGE>   1
                                                               EXHIBIT 4(c)(7)



                                SECOND AMENDMENT
                                       TO
                   THIRD AMENDED AND RESTATED CREDIT AGREEMENT


     This SECOND AMENDMENT TO THIRD AMENDED AND RESTATED CREDIT AGREEMENT
("Second Amendment") is made as of this 28th day of April, 2000 by and among
Credit Acceptance Corporation, a Michigan corporation ("Company"), the Permitted
Borrowers signatory hereto (each, a "Permitted Borrower" and collectively, the
"Permitted Borrowers"), Comerica Bank and the other banks signatory hereto
(individually, a "Bank" and collectively, the "Banks") and Comerica Bank, as
agent for the Banks (in such capacity, "Agent").


                                    RECITALS

     A. Company, Permitted Borrowers, Agent and the Banks entered into that
certain Third Amended and Restated Credit Agreement dated as of June 15, 1999
and a First Amendment dated as of December 10, 1999 (collectively, the "Credit
Agreement") under which the Banks renewed and extended (or committed to extend)
credit to the Company and the Permitted Borrowers, as set forth therein.

     B. The Company and the Permitted Borrowers have requested that Agent and
the Banks agree to a further amendment to the Credit Agreement and Agent and the
Banks are willing to do so, but only on the terms and conditions set forth in
this Second Amendment.

     NOW, THEREFORE, Company, Permitted Borrowers, Agent and the Banks agree:

     l.   The definition of Consolidated Tangible Net Worth in Section 1 of the
          Credit Agreement is hereby amended and restated in its entirety as set
          forth below, effective as of December 10, 1999:

                    "Consolidated Tangible Net Worth" shall mean the total
               preferred shareholders' investment and common shareholders'
               investment (common stock, paid in capital and retained earnings)
               as computed under GAAP, less assets properly classified as
               intangible assets according to GAAP, but excluding from the
               determination thereof, without duplication, any excess servicing
               asset resulting from the transfer, pursuant to a Permitted
               Securitization, of Advances to Dealers, Leased Vehicles,
               Installment Contracts (whether assigned outright or related to
               Advances to Dealers) or Leases (whether assigned outright or
               related to Leased Vehicles)."

     2.   Sections 7.5 and 7.6 of the Credit Agreement are amended, effective as
          of December 10, 1999, to change the word "excluding" (in the
          parenthetical phrase in the second line of each such section) to the
          word "including".


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                                                               EXHIBIT 4(c)(7)



     3.   This Second Amendment shall become effective, according to the terms
          and as of the date hereof, upon satisfaction by the Company and the
          Permitted Borrowers, on or before May 1, 2000, of the following
          conditions:

          (a)  Agent shall have received counterpart originals of this Second
               Amendment, in each case duly executed and delivered by Company,
               the Permitted Borrowers and the requisite Banks, in form
               satisfactory to Agent and the Banks;

          (b)  Agent shall have received from the Company and each of the
               Permitted Borrowers a certification (i) that all necessary
               actions have been taken by such parties to authorize execution
               and delivery of this Second Amendment, supported by such
               resolutions or other evidence of corporate authority or action as
               reasonably required by Agent and the Majority Banks and that no
               consents or other authorizations of any third parties are
               required in connection therewith; and (ii) that, after giving
               effect to this Second Amendment, no Default or Event of Default
               has occurred and is continuing on the proposed effective date of
               the Second Amendment;

          (c)  Agent shall have received, with a copy for each of the Banks,
               amendments to the Senior Debt Documents executed and delivered by
               the Company and the requisite holders of the Senior Debt, such
               amendments to be in form and substance satisfactory to the Agent
               and the Majority Banks; and

          If the foregoing conditions have not been satisfied or waived on or
          before May 1, 2000, this Second Amendment shall lapse and be of no
          further force and effect.

     4.   Each of the Company and the Permitted Borrowers ratifies and confirms,
          as of the date hereof and after giving effect to the amendments
          contained herein, each of the representations and warranties set forth
          in Sections 6.1 through 6.22, inclusive, of the Credit Agreement and
          acknowledges that such representations and warranties are and shall
          remain continuing representations and warranties during the entire
          life of the Credit Agreement.

     5.   Except as specifically set forth above, this Second Amendment shall
          not be deemed to amend or alter in any respect the terms and
          conditions of the Credit Agreement, any of the Notes issued thereunder
          or any of the other Loan Documents, or to constitute a waiver by the
          Banks or Agent of any right or remedy under or a consent to any
          transaction not meeting the terms and conditions of the Credit
          Agreement, any of the Notes issued thereunder or any of the other Loan
          Documents.

     6.   Unless otherwise defined to the contrary herein, all capitalized terms
          used in this Second Amendment shall have the meaning set forth in the
          Credit Agreement.


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                                                               EXHIBIT 4(c)(7)


     7.   This Second Amendment may be executed in counterpart in accordance
          with Section 13.10 of the Credit Agreement.

     8.   Comerica Bank - Canada having been designated by Comerica Bank, in its
          capacity as swing line bank (and as a Bank) under the Credit Agreement
          to fund Comerica Bank's advances in $C pursuant to Section 11.12 of
          the Credit Agreement, has executed this Second Amendment to evidence
          its approval of the terms and conditions thereof.

     9.   This Second Amendment shall be construed in accordance with and
          governed by the laws of the State of Michigan.

                     [SIGNATURES FOLLOW ON SUCCEEDING PAGES]


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                                                               EXHIBIT 4(c)(7)


     WITNESS the due execution hereof as of the day and year first above
written.


COMERICA BANK, as Agent                     CREDIT ACCEPTANCE CORPORATION

By: /S/ SCOTTIE S. KNIGHT                   By: /S/ BRETT A. ROBERTS
   ------------------------                    -----------------------
    Name: Scottie S. Knight                     Name: Brett A. Roberts
    Its:  Vice President                        Its:  Co-President
One Detroit Center
500 Woodward Avenue
Detroit, Michigan 48226
Attention: Michael P. Stapleton

COMERICA BANK - CANADA                      CREDIT ACCEPTANCE CORPORATION
                                            UK LIMITED

By: /S/ SCOTTIE S. KNIGHT                   By: /S/ BRETT A. ROBERTS
   ------------------------                    -----------------------
    Name: Scottie S. Knight                     Name: Brett A. Roberts
    Its:  Vice President                        Its:  Co-President

                                            CAC OF CANADA LIMITED

                                            By: /S/ BRETT A. ROBERTS
                                               -----------------------
                                                Name: Brett A. Roberts
                                                Its:  Co-President

                                            CREDIT ACCEPTANCE CORPORATION
                                            IRELAND LIMITED

                                            By: /S/ BRETT A. ROBERTS
                                               -----------------------
                                                Name: Brett A. Roberts
                                                Its:  Co-President


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                                                               EXHIBIT 4(c)(7)



BANKS:                             COMERICA BANK

                                   By: /S/ SCOTTIE S. KNIGHT
                                      ------------------------
                                       Name: Scottie S. Knight
                                       Its:  Vice President

                                   LASALLE BANK NATIONAL ASSOCIATION

                                   By: /S/ LISA MUN
                                      --------------------------------
                                       Name: Lisa Mun
                                       Its:  Assistant Vice President

                                   HARRIS TRUST AND SAVINGS BANK

                                   By: /S/ MICHAEL CAMELI
                                      ---------------------
                                       Name: Michael Cameli
                                       Its:  Vice President

                                   NATIONAL CITY BANK OF MINNEAPOLIS

                                   By: /S/ STEVEN R. BERGLUND
                                      -------------------------------
                                       Name: Steven R Berglund
                                       Its:  Assistant Vice President

                                   BANK OF AMERICA, N.A.

                                   By: /S/ ELIZABETH KURLECZ
                                      ------------------------
                                       Name: Elizabeth Kurlecz
                                       Its:  Managing Director

                                   THE BANK OF NOVA SCOTIA

                                   By: /S/ J. ERIC BERGREN
                                      ---------------------------
                                       Name: J. Eric Bergren
                                       Its:  Relationship Manager



                                                              Signature Page For
                                                            CAC Second Amendment