<PAGE>

                                                                    EXHIBIT 10.1

               SUPPLEMENT NO. 1 TO AMENDED AND RESTATED INDENTURE
                                       and
          AMENDMENT NO. 1 TO ANNEX A TO AMENDED AND RESTATED INDENTURE
                                      AND
                AMENDED AND RESTATED SALE AND SERVICING AGREEMENT

     This SUPPLEMENT NO. 1 TO AMENDED AND RESTATED INDENTURE and AMENDMENT NO. 1
TO ANNEX A TO AMENDED AND RESTATED INDENTURE AND AMENDED AND RESTATED SALE AND
SERVICING AGREEMENT, dated as of July ___, 2002 (this "Supplement"), is entered
into among AMERICREDIT MASTER TRUST (the "Issuer"), AMERICREDIT FUNDING CORP.
VII ("AFC"), AMERICREDIT FINANCIAL SERVICES, INC. ("AmeriCredit"), BANK ONE,
N.A. (the "Bank One"), and DEUTSCHE BANK TRUST COMPANY AMERICAS, formerly known
as Bankers Trust Company (the "Administrative Agent").


                                    RECITALS

     1.   The Issuer, AFC, in its capacity as a Seller, AmeriCredit, in its
capacity as a Seller and Servicer, and Bank One, in its capacity as a Backup
Servicer and Trust Collateral Agent, are parties to that certain Amended and
Restated Sale and Servicing Agreement dated as of February 22, 2002 (as amended,
supplemented or otherwise modified from time to time, the "Sale and Servicing
Agreement").

     2.   The Issuer, Bank One, in its capacity as Trustee, Backup Servicer and
Trust Collateral Agent, and the Administrative Agent are parties to that certain
Amended and Restated Indenture dated as of February 22, 2002 (as amended,
supplemented or otherwise modified from time to time, the "Indenture").

     3.   Annex A to the Sale and Servicing Agreement and the Indenture (as
amended, supplemented or otherwise modified from time to time, "Annex A")
defines certain capitalized terms that are used in the Sale and Servicing
Agreement and the Indenture.

     4.   The parties hereto desire to amend and supplement the Indenture and
Annex A as hereinafter set forth.

     NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties agree as follows:

     1.   Certain Defined Terms. Capitalized terms that are used herein without
definition and that are defined in Annex A shall have the same meanings herein
as therein.

     2.   Amendment to Indenture. The Indenture is hereby amended and
supplemented as follows:

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          2.1 Clause (xii) of the definition of Event of Default in Section 5.1
     of the Indenture is amended by deleting the following in its entirety:

          "(xii) Either (i) the long-term senior unsecured debt of AmeriCredit
     Corp. is rated by either S&P or Moody's below B or Ba3, respectively, or
     (ii) the long-term senior unsecured debt of AmeriCredit Corp. is not rated
     by both S&P and Moody's;"

     and substituting, in lieu thereof, the following:

          "(xii) [Intentionally Omitted];"

          2.2 The definition of Event of Default in Section 5.1 of the Indenture
     is amended by deleting the following clauses (xix) through (xxi) in their
     entirety:

          "(xix) The Tangible Net Worth of AmeriCredit Corp. shall be less than
     the sum of (a) $800,000,000 and (b) 75% of the cumulative positive net
     income (without deduction for negative net income) of AmeriCredit Corp. for
     each fiscal quarter since September 30, 2001, as reported in each annual
     report on Form 10-K and periodic report on Form 10-Q filed by AmeriCredit
     Corp. with the Securities and Exchange Commission;

          (xx) On any Determination Date, the Cumulative Net Loss Ratio for any
     Receivables Pool with a pool factor greater than 25% exceeds the amount set
     forth opposite the number of months since such Receivables Pool was
     securitized on Schedule 3 hereto; or

          (xxi) AFC shall cease to be a direct or indirect wholly-owned
     subsidiary of AmeriCredit; or AmeriCredit shall cease to be a direct or
     indirect wholly-owned subsidiary of AmeriCredit Corp.; or AFC and
     AmeriCredit shall at any time own less than 100% of the Certificates issued
     pursuant to the Trust Agreement."

     and substituting, in lieu thereof, the following:

          "(xix) The Tangible Net Worth of AmeriCredit Corp. shall be less than
     the sum of (a) $1,000,000,000 and (b) 75% of the cumulative positive net
     income (without deduction for negative net income) of AmeriCredit Corp. for
     each fiscal quarter having been completed since March 31, 2002, as reported
     in each annual report on Form 10-K and periodic report on Form 10-Q filed
     by AmeriCredit Corp. with the Securities and Exchange Commission;

          (xx) On any Determination Date, the Cumulative Net Loss Ratio for any
     Receivables Pool with a pool factor greater than 25% exceeds the amount set
     forth opposite the number of months since such Receivables Pool was
     securitized on Schedule 3 hereto;

          (xxi) AFC shall cease to be a direct or indirect wholly-owned
     subsidiary of AmeriCredit; or AmeriCredit shall cease to be a direct or
     indirect wholly-owned

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<PAGE>

     subsidiary of AmeriCredit Corp.; or AFC and AmeriCredit shall at any time
     own less than 100% of the Certificates issued pursuant to the Trust
     Agreement;

          (xxii) the ratio, expressed as a percentage, of the Adjusted Equity of
     AmeriCredit Corp. to the Managed Assets of AmeriCredit Corp shall be less
     than 6.5% as of any fiscal quarter end; or

          (xxiii) the average ratio of Adjusted EBITDA of AmeriCredit Corp. for
     the two most recently ended fiscal quarters of AmeriCredit Corp. to the
     Interest Expense of AmeriCredit Corp. for such two quarters shall be less
     than 1.2 to 1."

          2.3 A new Section 12.19 is hereby added at the end of Article XII of
     the Indenture as follows:

          12.19 Class D and Class E Note Proceeds. Notwithstanding any provision
          of this Indenture, including Section 3.13 hereof, to the contrary, the
          Issuer may apply the proceeds of the issuance of any Class D Notes or
          Class E Notes to repay the outstanding principal amount of, and
          accrued interest on, outstanding Class D Notes and/or Class E Notes.

     3. Amendment to Annex A. Annex A is hereby amended and supplemented as
follows:

          3.1 The following definitions are added in the appropriate
     alphabetical order:

          "Adjusted EBITDA" means, with respect to AmeriCredit Corp. for any
          period, earnings before interest, taxes, depreciation, and
          amortization, plus cash distributions from the trusts created in
          connection with securitizations sponsored by AmeriCredit minus any
          non-cash gain on the sale of receivables during such period, as
          determined in accordance with GAAP.

          "Adjusted Equity" means, with respect to AmeriCredit, at any time and
          determined in accordance with GAAP, the net worth of AmeriCredit at
          such time less the sum of (i) the intangible assets of AmeriCredit at
          such time and (ii) interest-only receivables of AmeriCredit from
          securitization trusts offset by any related interest rate swap
          valuation, adjusted for taxes (based on the effective tax rate as
          presented in the most recent report on Form 10-K or periodic report on
          Form 10-Q, as applicable, filed by AmeriCredit Corp. with the
          Securities and Exchange Commission) at such time.

          "GAAP" means, at any particular time, U.S. generally accepted
          accounting principles as in effect at such time, consistently applied.

          "Interest Expense" means, with respect to AmeriCredit Corp. on a
          consolidated basis and for any period, AmeriCredit Corp.'s interest
          expense during such period for money borrowed (exclusive of any such
          interest expense on any "off-balance


                                       3

<PAGE>

          sheet" securitizations or "off-balance sheet" warehouse facilities),
          calculated in accordance with GAAP.

          "Managed Assets" means, as of any date, the aggregate outstanding
          balance of all receivables (whether or not thereafter sold or disposed
          of) that are serviced by the Servicer or any of its Affiliates as of
          such date, calculated in a manner consistent with the components of
          "managed receivables" in the most recent reports on Form 10-K or Form
          10-Q filed by AmeriCredit Corp.

          3.2 Each of the following definitions is amended by deleting such
     definition in its entirety and substituting, in lieu thereof, the
     applicable definition set forth below:

          "Cumulative Net Losses" means, as of any date, for any Receivables
          Pool, the aggregate cumulative amount of Gross Charge-Offs of
          receivables in such Receivables Pool as of the end of the preceding
          Collection Period net of all Recoveries with respect to any such
          receivables as of the end of the preceding Collection Period.

          "Defaulted Receivable" means, with respect to any date, either, as the
          context may require, (a) a Receivable with respect to which (i) all or
          any portion in excess of 5% of a Scheduled Receivable Payment is more
          than 90 days past due, (ii) the Servicer has repossessed the related
          Financed Vehicle (and any applicable redemption period has expired),
          (iii) the Obligor has been identified in the records of the Servicer
          as being the subject of a current bankruptcy proceeding or (iv) such
          Receivable is in default and the Servicer has charged-off such
          Receivable in accordance with its standard policies or otherwise has
          determined in good faith that payments thereunder are not likely to be
          resumed or (b) with respect to the Servicing Portfolio or any portion
          thereof, a receivable with respect to which (i) all or any portion in
          excess of 5% of a scheduled payment is more than 90 days past due,
          (ii) the Servicer has repossessed the related Financed Vehicle (and
          any applicable redemption period has expired), (iii) the Obligor has
          been identified in the records of the Servicer as being the subject of
          a current bankruptcy proceeding or (iv) such receivable is in default
          and the Servicer has charged-off such receivable in accordance with
          its standard policies or otherwise has determined in good faith that
          payments thereunder are not likely to be resumed.

          "Financed Vehicle" means, in respect of a Receivable or a receivable
          in the Servicing Portfolio, an automobile or light-duty truck, van or
          minivan, together with all accessions thereto, securing an Obligor's
          indebtedness under the respective Receivable or receivable.

          "Gross Charge-Offs" means, with respect to any Collection Period, with
          respect to the receivables in any Receivables Pool or the Servicing
          Portfolio, the aggregate principal balances of all such receivables
          (i) as to which 5% or more of a scheduled receivable payment shall
          have become 120 or more days delinquent (excluding receivables for
          which the Financed Vehicle has been repossessed and receivables for
          which the Obligor is bankrupt), or (ii) that the Servicer has


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          charged-off (or in respect of which the Servicer has otherwise
          determined in good faith that payments relating thereto are not likely
          to be resumed).

          "Level III Trigger Event" means, on any Distribution Date, that the
          average of the Receivables Pool Servicer Delinquency Ratios as of the
          last day of the preceding Collection Period, as of the last day of the
          second preceding Collection Period and as of the last day of the third
          preceding Collection Period for any Receivables Pool exceeds the
          amount set forth opposite the number of months since such Receivables
          Pool was securitized on Schedule 5 to the Indenture.

          "Loss Ratio" means, as of any date, the ratio (expressed as a
          percentage) computed by dividing "A" by "B" and multiplying the result
          by "C", where "A" equals the aggregate amount of Gross Charge-Offs of
          Contracts in the Servicing Portfolio during the six Collection Periods
          immediately preceding such date net of all recoveries with respect to
          any such Contracts (including post-disposition amounts received on
          previously charged-off Contracts) divided by the average aggregate
          principal balance of all Contracts in the Servicing Portfolio during
          such six Collection Periods, where "B" equals the actual number of
          days in such six Collection Periods and where "C" equals the actual
          number of days in the fiscal year of the Servicer in which the most
          recent Collection Period ended.

          "Monthly Extension Rate" means, with respect to any Determination
          Date, the fraction, expressed as a percentage, the numerator of which
          is the aggregate principal balance of all receivables in the Servicing
          Portfolio whose payments were extended during the related Collection
          Period and the denominator of which is the aggregate principal balance
          of all receivables in the Servicing Portfolio as of the close of
          business on the last day of the Collection Period immediately
          preceding such related Collection Period.

          "Obligor" on a Receivable or a receivable in the Servicing Portfolio
          means the purchaser or co-purchasers of the Financed Vehicle and any
          other Person who owes payments under such Receivable or receivable.

          "Receivables Pool" means, with respect to any date of determination,
          each receivables pool supporting an asset-backed securitization
          sponsored by AmeriCredit on and after the date two years prior to such
          date of determination (excluding any receivables held as part of any
          warehouse arrangement).

          "Receivables Pool Servicer Delinquency Ratio" means, as of the last
          day of a Collection Period, for any Receivables Pool, the ratio,
          expressed as a percentage, computed by dividing (i) the aggregate
          principal balance on such date of each receivable in such Receivables
          Pool with respect to which more than 5% of a scheduled payment is more
          than 60 days past due (excluding a receivable for which the financed
          vehicle has been repossessed and the proceeds thereof have not been
          realized by the Servicer) by (ii) the aggregate principal balance of
          all receivables in such Receivables Pool on the first day of such
          Collection Period.


                                       5

<PAGE>

          "Recoveries" means, with respect to any Defaulted Receivable, monies
          collected in respect thereof (other than Scheduled Receivable Payments
          or scheduled payments, as the context may require, collected from the
          related Obligor which cause such Receivable or receivable, as the
          context may require, to be no longer a Defaulted Receivable), from
          whatever source (including those received from Titled Third-Party
          Lenders), during any Collection Period, net of the sum of any
          reasonable expenses incurred by the Servicer in connection with the
          collection, repossession and disposition of the related Financed
          Vehicle and any amounts required by law to be remitted to the related
          Obligor; provided that Recoveries with respect to any Defaulted
          Receivable shall in no event be less than zero.

          "Servicer Delinquency Ratio" means, as of the last day of a Collection
          Period, the ratio, expressed as a percentage, computed by dividing (i)
          the aggregate principal balance on such date of each receivable in the
          Servicing Portfolio with respect to which more than 5% of a scheduled
          payment is more than 60 days past due (including a receivable for
          which the financed vehicle has been repossessed and the proceeds
          thereof have not been realized by the Servicer) by (ii) the aggregate
          principal balance of all receivables in the Servicing Portfolio on the
          last day of such Collection Period.

     4.   Effect of Supplement. Except as expressly amended and modified by this
Supplement, all provisions of the Sale and Servicing Agreement, the Indenture
and Annex A shall remain in full force and effect. After this Supplement becomes
effective, all references in the Sale and Servicing Agreement, the Indenture or
Annex A to "this Sale and Servicing Agreement", "this Indenture", "this Annex
A", "hereof", "herein" or words of similar effect referring to the Sale and
Servicing Agreement, the Indenture or Annex A shall be deemed to be references
to the Sale and Servicing Agreement, the Indenture or Annex A, respectively, as
amended by this Supplement. This Supplement shall not be deemed to expressly or
impliedly waive, amend or supplement any provision of the Sale and Servicing
Agreement, the Indenture or Annex A other than as expressly set forth herein.

     5.   Effectiveness. This Supplement shall become effective as of the date
hereof upon receipt by the Trustee of counterparts of this Supplement (whether
by facsimile or otherwise) executed by each of the other parties hereto and by
Noteholders representing the Class A Majority, the Class B Majority and the
Class C Majority, receipt by the Trustee of an opinion of counsel satisfying the
requirements of Section 11.1 of the Sale and Servicing Agreement, and
satisfaction of the Rating Agency Condition; provided that this Supplement shall
cease to be effective if the annual report on Form 10-K filed by AmeriCredit
Corp. with the Securities and Exchange Commission with respect to the fiscal
year ended June 30, 2002 shows a material adverse change in the condition
(financial or otherwise), business, operations, results of operations, or
properties of AmeriCredit Corp. and its subsidiaries since March 31, 2002.

     6.   Counterparts. This Supplement may be executed in any number of
counterparts and by different parties on separate counterparts, and each
counterpart shall be deemed to be an original, and all such counterparts shall
together constitute but one and the same instrument.


                                       6

<PAGE>

     7.   Governing Law. This Supplement shall be governed by, and construed in
accordance with, the internal laws of the State of New York without regard to
any otherwise applicable principles of conflicts of law.

     8.   Section Headings. The various headings of this Supplement are inserted
for convenience only and shall not affect the meaning or interpretation of this
Supplement, the Indenture or Annex A or any provision hereof or thereof.

     9.   Representations and Warranties. Each of the Issuer, AFC and
AmeriCredit, as applicable, represent and warrant that (i) all of their
respective representations and warranties set forth in the Sale and Servicing
Agreement and the Indenture are true and accurate in all material respects as
though made on and as of the date hereof (except representations and warranties
which relate to a specific date, which were true and correct as of such date)
and (ii) no Servicer Termination Event or Event of Default under either the Sale
and Servicing Agreement or the Indenture has occurred and is continuing.

                  [remainder of page intentionally left blank]


                                       7

<PAGE>

     IN WITNESS WHEREOF, the parties have executed this Supplement as of the
date first written above.

                                       AMERICREDIT MASTER TRUST, as Issuer

                                       By:    DEUTSCHE BANK TRUST COMPANY
                                       DELAWARE, not in its individual capacity
                                       but solely as Owner Trustee on behalf of
                                       the Trust

                                       By:
                                              ----------------------------------
                                       Name:
                                              ----------------------------------
                                       Title:
                                              ----------------------------------

                                       AMERICREDIT FUNDING CORP. VII, as Seller

                                       By:
                                              ----------------------------------
                                       Name:
                                              ----------------------------------
                                       Title:
                                              ----------------------------------

                                       AMERICREDIT FINANCIAL SERVICES, INC., as
                                       Seller and Servicer

                                       By:
                                              ----------------------------------
                                       Name:
                                              ----------------------------------
                                       Title:
                                              ----------------------------------

                                       BANK ONE, N.A., as Backup Servicer, Trust
                                       Collateral Agent, and Trustee

                                       By:
                                              ----------------------------------
                                       Name:
                                              ----------------------------------
                                       Title:
                                              ----------------------------------

                                       DEUTSCHE BANK TRUST COMPANY AMERICAS,
                                       formerly known as Bankers Trust Company,
                                       as Administrative Agent

                                       By:
                                              ----------------------------------
                                       Name:
                                              ----------------------------------
                                       Title:
                                              ----------------------------------

                                       By:
                                              ----------------------------------
                                       Name:
                                              ----------------------------------
                                       Title:
                                              ----------------------------------

<PAGE>

AGREED AND CONSENTED TO:

[NAME OF COMMITTED PURCHASER],
     as Class A-1 Committed Purchaser, Class A-2
     Committed Purchaser, Class B Committed
     Purchaser, Class C Committed Purchaser
     and Agent

By:
     ----------------------------------
     Name:
     Title:

By:
     ----------------------------------
     Name:
     Title:

[NAME OF CONDUIT PURCHASER],
     as Class A Owner, Class B Owner and Class C Owner

By:
     ----------------------------------
     Name:
     Title: