<PAGE>

                         Joint Review Board Agreement
                         ----------------------------

The purpose of this letter is to formalize the agreement that has been reached
between AM General Corporation ("AMG") and General Motors Corporation ("GM"), in
connection with the New Vehicle Assembly Agreement  and other agreements by and
between GM and AMG dated December 21, 1999, relating to the formation of a joint
review board to, among other things, be utilized as a tool to assist the parties
in managing their business relationship.  In this regard, the parties agree as
follows:


1.   On the Closing Date, GM and AMG shall create a review board for the purpose
     of monitoring and administering the agreements set forth in Section 1 of
     the Master Agreement by and between GM and AMG. GM and AMG shall each be
     entitled, during the term of the New Vehicle Assembly Agreement to appoint
     two members to the Joint Review Board ("JRB") and to replace any member
     thus appointed by a new member upon written notice to the other party. All
     four members must be in attendance in order to constitute a JRB meeting.

2.   The JRB should meet on a regular basis (as determined by the members
     recognizing that the frequency of the meetings will vary depending upon the
     stage of the various agreements), but not less than twice per year. Meeting
     locations and times will be mutually agreed upon by the parties.

3.   Agenda items for the JRB shall be mutually determined and may include the
     following topics (consisting of summary information and issues relevant to
     the topic) on a regular basis (agenda items will vary depending upon the
     stage of the various agreements):

          (a)  Monitoring and administering the Management Services Agreement
          (including any successor agreement(s) thereto) for the Current
          Vehicle, including but not limited to:

          .    Review potential impacts relative to proposed price changes;

          .    Review GM market, advertising and promotional plans;

          .    Review proposed changes to the existing dealer and distributor
               network;

          .    Review historical and forecast volume performance;

          .    Review significant product change proposals;

          .    Resolve disputes regarding the operation of the agreement(s); and

          .    Other topics as may be mutually agreed upon by the parties

          (b)  Monitoring and administering the New Vehicle Assembly Agreement
          for the New Vehicle, including but not limited to:

          .    Review progress of the entire program prior to start-up
               (including but not limited to specific issues per Section 4.2 of
               the New Vehicle Assembly Agreement);

          .    Review order and schedule data (including long term forecast
               information);

          .    Review GM market, advertising and promotional plans;

          .    Review warranty history, quality control data and other relevant
               product quality information;

          .    Review significant product change proposals (including New
               Vehicle Design Specification, New Vehicle Assembly Specification
               and New Vehicle Quality Control Standards) and upon acceptance,
               progress of the product changes through start-up of the specific
               changes;

          .    Review Product Change Proposals (PCP) rejected by the Product
               Change Forum (PCF) at the discretion of the proposal originator.
               After JRP discussion the originator may decide to resubmit the
               PCP (or a revised PCP) to the PCF for further consideration;

          .    Review relevant JD Powers information, including the setting of
               targets;

          .    Resolve disputes regarding the operation of the agreement; and

                                      -1-
<PAGE>

          .    Other topics as may be mutually agreed upon by the parties.

     (c)  Identifying potential new manufacturing opportunities for AMG and
          the New Vehicle Facilities, including but not limited to:

          .    New / additional projects to be considered concurrently with the
               New Vehicle Assembly Agreement;

          .    Future potential use of the New Vehicle Facilities upon
               expiration of the New Vehicle Assembly Agreement;

          .    Establishing evaluation criteria for future consideration;

          .    Evaluating proposed new projects to be undertaken jointly by GM
               and AMG; and

          .    Other topics as may be mutually agreed upon by the parties.

4.   The primary function of the JRB shall be consultative and advisory. The JRB
     may submit recommendations to GM and / or AMG, but neither GM nor AMG shall
     be obligated to follow such recommendations.

5.   The JRB is not intended to replace communications and normal business
     relations at the appropriate levels within each company's organization. The
     JRB is intended to allow a formal review process, ensuring common
     understanding and business objectives between the parties and providing an
     avenue to resolve issues that cannot be resolved at the normal points of
     contacts of the two companies.

This letter agreement shall be governed by the laws of the State of Michigan
without regard to the principles of conflicts of law, shall be binding and inure
to the benefit of AMG and GM and their respective successors and assigns, and
may only be modified or amended by a written document duly executed by both
parties.



GENERAL MOTORS CORPORATION               AM GENERAL CORPORATION



          1)  By: ____________________        By: ____________________

Section 12.   Title: _________________        Title: _________________

                                      -2-