<PAGE>

                                                                   Exhibit 10.25
                                                                   -------------

                              Louis M. Brown, Jr.
                                4801 Maury Lane
                          Alexandria, Virginia  22304


                                 August 3, 2000

Precision Auto Care, Inc.
748 Miller Drive, S.E.
Leesburg, Virginia 20175
Attention: Board of Directors

                                   AGREEMENT
                                   ---------

Ladies and Gentlemen:

     This letter agreement (the "Agreement") sets forth our mutual understanding
regarding the purchase by me ("Buyer") of 1,700,000 shares of Common Stock of
Precision Auto Care, Inc. (the "Company") and the Buyer's employment with the
Company.  The terms and conditions of the Agreement are as follows:

     1.  Purchase of Common Stock.  Subject to the terms and conditions set
         ------------------------
forth herein and as an inducement to Buyer to accept employment with the
Company, the Company hereby agrees to issue and sell to Buyer, and Buyer hereby
agrees that it will purchase from the Company, on August 4, 2000 (the "Closing
Date"), 1,700,000 shares of Common Stock of the Company (the "Shares") for an
aggregate purchase price of $750,000 (the "Purchase Price").

     2.  Employment Matters.  The Buyer shall be appointed the Chief Executive
         ------------------
Officer of the Company, effective as of the Closing Date.  The Buyer will serve
in that capacity at the pleasure of the Board of Directors until his successor
has been duly elected and appointed by the Company's Board of Directors.  During
the first year Buyer serves as the Chief Executive Officer of the Company, the
Buyer will receive a salary of $1.00.  Thereafter, the Buyer shall be entitled
to receive a base salary and other compensation as may be determined by the
Board of Directors of the Company.  The Board of Directors shall appoint Buyer
to serve as a Class II director of the Company (with a term expiring at the
annual meeting of the shareholders in 2002) as soon as is reasonably practicable
following the Closing Date.

     3.  Representations and Warranties of the Company. The Company represents
         ---------------------------------------------
and warrants to Buyer as follows:

         (a)  Corporate Existence and Power.  The Company (i) is a corporation
              -----------------------------
duly organized, validly existing and in good standing under the laws of the
Commonwealth of Virginia; (ii) has all requisite corporate power and authority
to own and operate its property, to lease the property it operates as lessee and
to conduct the business in which it is currently, or is
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August 3, 2000
Page 2

currently proposed to be, engaged; (iii) is duly qualified as a foreign
corporation, licensed and in good standing under the laws of each jurisdiction
to which its ownership, lease or operation of property or the conduct of its
business requires such qualification; and (iv) has the corporate power and
authority to execute, deliver and perform its obligations under this Agreement.

          (b)  Authorization; No Contravention. The execution, delivery and
               -------------------------------
performance by the Company of this Agreement and the transactions contemplated
hereby, including, without limitation, the sale, issuance and delivery of the
Shares, the hiring of Buyer as the Company's Chief Executive Officer and the
appointment of Buyer to the Company's Board of Directors, (i) have been duly
authorized by all necessary corporate action of the Company; (ii) do not
contravene the terms of the Articles of Incorporation or the Bylaws of the
Company; (iii) do not violate, conflict with or result in any breach or
contravention of, or the creation of any lien under, any contractual obligation
of the Company, or any requirement of law applicable to the Company; and (iv) do
not violate any judgment, injunction, writ, award, decree or order
(collectively, "Orders") of any nature of any governmental authority against, or
binding upon, the Company. The Company has not previously entered into any
contractual obligation that is currently in effect or by which it is currently
bound, granting any rights to any third party that are inconsistent with the
rights to be granted by the Company in this Agreement.

          (c)  Governmental Authorization; Third Party Consents.  No approval,
               ------------------------------------------------
consent, compliance, exemption, authorization or other action by, or notice to,
or filing with, any third party or governmental authority in respect of any
requirement of law is necessary or required in connection with the execution,
delivery or performance by or enforcement against the Company of this Agreement
or the transactions contemplated hereby.

          (d)  Binding Effect. This Agreement has been duly executed and
               --------------
delivered by the Company and constitutes the legal, valid and binding obligation
of the Company enforceable against the Company in accordance with its terms,
except as enforceability may be limited by applicable bankruptcy, insolvency,
reorganization, fraudulent conveyance or transfer, moratorium or similar laws
and by general principles of equity relating to enforceability (regardless of
whether considered in a proceeding at law or in equity).

          (e)  Litigation. The Company has not received notice of any Order and
               ----------
to the knowledge of the Company no Order has been issued by any court or other
governmental authority against the Company purporting to enjoin or restrain the
execution, delivery or performance of any of the transactions contemplated by
this Agreement.

          (f)  Compliance with Laws. The Company is in compliance with all
               --------------------
requirements of law and all Orders issued by any court or governmental authority
in all material respects.

          (g)  Capitalization. On the Closing Date, after giving effect to the
               --------------
transactions contemplated by this Agreement, the authorized capital stock of the
Company shall consist of 19,000,000 shares of Common Stock, of which 8,071,144
shares will be issued and outstanding, and 1,000,000 shares of Preferred Stock,
none of which will be outstanding. The Shares are duly authorized, and, when
issued to Buyer pursuant to the terms of this Agreement, will be validly
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August 3, 2000
Page 3

issued, fully paid and nonassessable and will be issued in compliance with the
registration and qualification requirements of all applicable securities laws.
The issued and outstanding shares of capital stock of the Company are all duly
authorized, validly issued, fully paid and nonassessable, and were issued in
compliance with the registration and qualification requirements of all
applicable securities laws.


          (h)  Financial Statements.  The financial statements of the Company
               --------------------
(balance sheet and statements of operations, cash flows and shareholders'
equity, together with the notes thereto) for the fiscal year ended June 30, 1999
and the three quarters ended March 31, 2000 (the "Financial Statements") are
complete and correct in all material respects and have been prepared in
accordance with GAAP applied on a consistent basis throughout the periods
indicated and with each other. The Financial Statements fairly present in all
material respects the financial position, operating results and cash flows of
the Company as of the dates and for the respective periods indicated.

     4.   Representations/Warranties and Covenants of the Buyer.  The Buyer
          -----------------------------------------------------
represents, warrants and covenants to Buyer as follows:


          (a)  Accredited Investor/Securities Laws.  Buyer is an accredited
               -----------------------------------
investor within the meaning of Securities and Exchange Commission Rule 501(a).
Buyer understands that the Shares have not been registered under the Securities
Act of 1933, as amended (the "Securities Act"), or under the laws of any other
jurisdiction and that the Company does not contemplate registering the Shares.
Buyer understands that the Shares may not be sold, transferred, pledged or
otherwise disposed of unless they are subsequently registered under the
Securities Act and, where required, under the laws of other jurisdictions or an
exemption from registration is available and the Company has received an opinion
of counsel satisfactory to the Company to that effect. Buyer is acquiring the
Shares solely for his own account, solely for investment not with a view to or
for resale, distribution or other disposition. Buyer has made no contract,
undertaking, agreement or arrangement, and has no plans to enter into any
contract, undertaking, agreement or arrangement for any resale, distribution or
disposition of the Shares. Buyer agrees that none of the Shares will be resold
in the absence of either an effective registration statement covering the Shares
under the Securities Act or an opinion of counsel satisfactory to the Company
that registration is not required under the Securities Act or under applicable
laws of any other jurisdiction.

          (b)  Permitted Transfers.  Notwithstanding anything in this Section
               -------------------
4 to the contrary, the Company acknowledges that Buyer may transfer a portion of
the Shares, with or without consideration therefor, to (1) other individuals to
induce them to join the senior management team of the Company, (2) to immediate
family members and children of immediate family members, or entities for which
such individuals are beneficiaries, in connection with estate planning, and
Buyer shall not require a legal opinion with respect to any such transfer.

          (c)  Restrictive Legend.  Buyer understands that the certificates
               ------------------
representing the Shares will bear the restrictive legend set forth below:
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August 3, 2000
Page 4

     "The securities represented by this certificate have not been registered
     under the Securities Act of 1933, as amended, under the Virginia Securities
     Act, or under the securities acts of any other state or jurisdiction.  No
     sale, offer to sell or other transfer of these securities may be made
     unless pursuant to an effective registration statement, or unless in the
     opinion of counsel to the issuer the proposed disposition may be made
     pursuant to a valid exemption from the registration provisions of these
     Acts."

               (d)  The terms of this Agreement do not conflict with any
agreement to which the Buyer is a party. Without limiting the generality of the
foregoing, the Buyer is not under any obligation under the terms of a
noncompetition or other agreement that will restrict Buyer's ability to serve as
Chief Executive Officer of the Company.

     5.   Conditions to the Obligation of Buyer to Close.  The obligation of
          ----------------------------------------------
Buyer to purchase the Shares shall be subject to the satisfaction as determined
by, or waiver by, Buyer of the following conditions on or before the Closing
Date:

          (a)  Refinancing.  The Company shall have received the form of
               -----------
attached hereto as Exhibit A (the "Commitment Letter") duly executed by all of
                   ---------
the parties thereto and shall have received the sum of $2,500,000 in the Bridge
Loan financing contemplated by numbered paragraph 3 thereof.

          (b)  Representation and Warranties.  The representations and
               -----------------------------
warranties of the Company contained in Section 2 hereof shall be true and
correct in all material respects at and on the Closing Date as if made at and on
such date.

          (c)  Compliance with this Agreement.  The Company shall have
               ------------------------------
performed and complied in all material respects with all of its agreements and
conditions set forth herein that are required to be performed or complied with
by the Company on or before the Closing Date.

          (d)  Bankruptcy.  The Company shall not have filed a petition for
               ----------
bankruptcy, reorganization or rearrangement under any federal or state
bankruptcy or file, any such involuntary petition against the Company.

          (e)  Foreclosure. No creditor shall have commenced any foreclosure
               -----------
proceedings against any assets of the Company.

          (f)  No Commitment to Issue Additional Securities.  Except as set
               --------------------------------------------
forth on  Schedule 5(f) hereto and as contemplated by the terms of the
          -------------
Commitment Letter, there shall be no existing contracts, agreements or
understandings obligating the Company to issue additional equity securities in
the Company.

          (g)  No Material Adverse Event.  There shall have been no events that
               -------------------------
have been materially adverse to the Company's business, results of operations or
financial condition.
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August 3, 2000
Page 5

          (h)  Secretary's Certificate.  Buyer shall have received a certificate
               -----------------------
from the Company, in form and substance satisfactory to Buyer, dated the Closing
Date and signed by the Secretary or an Assistant Secretary of the Company,
certifying (a) that the attached copies of the Articles of Incorporation, the
Bylaws and resolutions of the Board of Directors of the Company approving this
Agreement and the transactions contemplated hereby, are true, complete and
correct and remain unamended and in full force and effect and (b) as to the
incumbency and specimen signature of each officer of the Company executing this
Agreement and any other document delivered in connection herewith on behalf of
the Company.

          (i)  Officer's Certificate.  Buyer shall have received a certificate
               ---------------------
from the Company, in form and substance satisfactory to Buyer, dated the Closing
Date and signed by the Chief Executive Officer of the Company, certifying (a)
the representations and warranties of the Company contained in Section 2 hereof
are true and correct in all material respects at and on the Closing Date and (b)
the Company has performed and complied in all material respects with all of the
agreements and conditions set forth or contemplated herein that are required to
be performed or complied with by the Company on or before the Closing Date.

          (j)  Purchased Shares.  The Company shall have delivered to Buyer a
               ----------------
certificate in definitive form representing the Shares purchased by Buyer on the
Closing Date.

          (k)  Registration Rights.  The Company shall have executed a
               -------------------
registration rights agreement with the Buyer in the form attached hereto as
Exhibit B.
---------

          (l)  Board Approval. The transactions contemplated by this Agreement ,
including the issuance and sale of the Shares, shall have been duly approved by
the Company's Board of Directors, including a majority of the disinterested
directors.

     6.   Conditions to the Obligation of the Company to Close. The obligation
          ----------------------------------------------------
of the Company to issue, sell and deliver the Shares to Buyer shall be subject
to delivery by Buyer to the Company of $750,000 in immediately available funds.
The Company shall also have received the Commitment Letter duly executed by all
of the parties thereto, and received the sum of $2,500,000 in Bridge Loan
financing contemplated by numbered paragraph 3 thereof.

     7.   Termination of Agreement.  This Agreement may be terminated prior to
          ------------------------
the Closing Date as follows:

          (a)  at any time on or prior to the Closing Date, by mutual written
consent of the Company and Buyer; or

          (b)  at the election of either the Company or Buyer by written notice
to the other party after 5:00 p.m., Richmond, Virginia, time on August __, 2000,
if the transactions contemplated by this Agreement shall not have been
consummated pursuant hereto unless such date is extended by the mutual written
consent of the Company and Buyer.

If this Agreement so terminates, it shall become null and void and have no
further force or effect.
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August 3, 2000
Page 6

     8.   Miscellaneous.
          -------------

          (a)  Survival of Representations and Warranties.  All of the
               ------------------------------------------
representations and warranties made herein shall survive the execution and
delivery of this Agreement for a period of two years.

          (b)  Publicity.  Buyer and Company will consult with each other before
               ---------
holding any press conferences, analyst calls or other meetings or discussions
and before issuing any press releases or other public announcements or
statements regarding the transactions contemplated herein. The parties will
provide each other the reasonable opportunity to review and comment upon any
press release or other public announcement or statement with respect to the
transactions contemplated by this Agreement and shall not issue any such press
release or other public announcement or statement prior to such consultation,
except as may be required by applicable law. The parties agree that the initial
press release or releases to be issued with respect to the transactions
contemplated by this Agreement shall be mutually agreed upon prior to the
issuance thereof.

          (c)  Notices.  All notices, demands and other communications provided
               -------
for or permitted hereunder shall be made in writing and shall be by registered
or certified first-class mail, return receipt requested, telecopier, courier
service or personal delivery:

               (i)  if to the Company:
                    Precision Auto Care, Inc.
                    748 Miller Drive, S.E.
                    Leesburg, Virginia 20175
                    Attention:
                    Facsimile:

               with a copy to:

                    Miles & Stockbridge P.C.
                    10 Light Street
                    Baltimore, Maryland 21202
                    Attention: John B. Frisch
                    Facsimile: (410) 385-3700

                    and

               (ii) if to Buyer:

                    Louis M. Brown, Jr.
                    4801 Maury Lane
                    Alexandria, Virginia 22304
                    Facsimile: 703-923-4021
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August 3, 2000
Page 7

                         with a copy to:

                              Hunton & Williams
                              951 East Byrd Street
                              Richmond, Virginia 23219
                              Attention: Thurston R. Moore
                              Facsimile: (804) 788-8218

     All such notices and communications shall be deemed to have been duly given
when delivered by hand, if personally delivered; when delivered by courier, if
delivered by commercial courier service; five Business Days after being
deposited in the mail, postage prepaid, if mailed; and when receipt is
mechanically acknowledged, if telecopied.

          (d)  Successors and Assigns; Third Party Beneficiaries.  This
               -------------------------------------------------
Agreement shall inure to the benefit of and be binding upon the successors and
permitted assigns of the parties hereto. Subject to applicable securities laws
Buyer may assign any of his continuing rights under this Agreement pursuant to
transfers of a portion of the Shares in accordance with Section 4 hereof. The
Company may not assign any of their rights under this Agreement without the
written consent of Buyer. No Person other than the parties hereto and their
successors and permitted assigns is intended to be a beneficiary of this
Agreement

          (e)  Amendment and Waiver.
               --------------------

               (i)  No failure or delay on the part of the Company or Buyer in
     exercising any right, power or remedy hereunder shall operate as a waiver
     thereof, nor shall any single or partial exercise of any such right, power
     or remedy preclude any other or further exercise thereof or the exercise of
     any other right, power or remedy. The remedies provided for herein are
     cumulative and are not exclusive of any remedies that may be available to
     the Company or Buyer at Law, in equity or otherwise.

               (ii) Any amendment, supplement or modification of or any
     provision of this Agreement, any waiver of any provision of this Agreement,
     and any consent to any departure by the Company or Buyer from the terms of
     any provision of this Agreement, shall be effective (i) only if it is made
     or given in writing and signed by the Company and Buyer, and (ii) only in
     the specific instance and for the specific purpose for which made or given.
     Except where notice is specifically required by this Agreement, no notice
     to or demand on the Company in any case shall entitle the Company to any
     other or further notice or demand in similar or other circumstances.

          (f)  Counterparts; Facsimile. This agreement may be executed in any
               -----------------------
     number of counterparts and by the parties hereto in separate counterparts,
     each of which when so executed shall be deemed to be an original and all of
     which taken together shall constitute one and the same agreement, and may
     be delivered to the other parties hereto by facsimile.
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August 3, 2000
Page 8

          (g)  Headings.  The headings in this Agreement are for convenience of
               --------
reference only and shall not limit or otherwise affect the meaning hereof.

          (h)  Governing Law.  THIS AGREEMENT SHALL BE GOVERNED BY AND
               -------------
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE COMMONWEALTH OF VIRGINIA,
WITHOUT REGARD TO THE PRINCIPLES OF CONFLICTS OF LAW THEREOF.

          (i)  Severability. If any one or more of the provisions contained
               ------------
herein, or the application thereof in any circumstance, is held invalid, illegal
or unenforceable in any respect for any reason, the validity, legality and
enforceability of any such provision in every other respect and of the remaining
provisions hereof shall not be in any way impaired, unless the provisions held
invalid, illegal or unenforceable shall substantially impair the benefits of the
remaining provisions hereof.

          (j)  Rules of Construction. Unless the context otherwise requires,
               ---------------------
references to sections or subsections refer to sections or subsections of this
Agreement.

          (k)  Entire Agreement. This Agreement is intended by the parties as a
               ----------------
final expression of their agreement and intended to be a complete and exclusive
statement of the agreement and understanding of the parties hereto in respect of
the subject matter contained herein and therein. There are no restrictions,
promises, representations, warranties or undertakings, other than those set
forth or referred to herein or therein. This Agreement supersedes all prior
agreements and understandings between the parties with respect to such subject
matter.

          (l)  Further Assurances. Each of the parties shall execute such
               ------------------
documents and perform such further acts (including, without limitation,
obtaining any consents, exemptions, authorizations or other actions by, or
giving any notices to, or making any filings with, any governmental authority or
any other third party) as may be reasonably required or desirable to carry out
or to perform the provisions of this Agreement.
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August 3, 2000
Page 9


     If you are in agreement with the foregoing, please so acknowledge by
executing the enclosed copy of this Agreement and returning it to the
undersigned by 5:00 p.m., Eastern Standard Time, on August 3, 2000.

                              Very truly yours,

                              /s/ Louis M. Brown, Jr.
                              -----------------------
                              Louis M. Brown, Jr.


ACCEPTED AND AGREED
as of August 4, 2000

PRECISION AUTO CARE, INC.


By: /s/ Woodley A. Allen
    --------------------
    Name: Woodley A. Allen
    Title: Chairman Board of Directors
<PAGE>

August 3, 2000
Page 10

                                                                   SCHEDULE 5(f)

Existing Contracts, Agreements or Understandings Obligating the Company to Issue
--------------------------------------------------------------------------------
Additional Equity Securities.
----------------------------

     (a)  Stock Options Held by Officers, Directors and Employees:

     .    The Company has issued options to purchase 742,875 shares of the
          Company's Common Stock pursuant various stock options plans and
          private agreements with individual officers, directors and employees.

     .    175,000 shares of Common Stock have been reserved for issuance under
          the Precision Tune Stock Option Plan, adopted September 28, 1995, and
          amended and restated August 27, 1997. 135,500 shares are available for
          additional grants under this plan, which expires September 28, 2005.

     .    400,000 shares of Common Stock have been reserved for issuance under
          the 1997 Precision Auto Care Stock Option Plan, adopted November 5,
          1997. 198,000 shares are available for additional grants under this
          plan, which expires November 5, 2007.

     .    600,000 shares of Common Stock have been reserved for issuance under
          the 1999 Precision Auto Care Employee Stock Option and Restricted
          Stock Plan, adopted March 31, 1999. 131,125 shares are available for
          additional option grants and restricted stock awards under this plan,
          which expires March 31, 2009.

     .    75,000 shares of Common Stock have been reserved for issuance under
          the Precision Auto Care, Inc. 1998 Outside Directors' Stock Option
          Plan. Pursuant to the terms of this plan on the date of the company's
          on the date of each annual meeting of shareholders, options to
          purchase 2,500 shares are automatically due to be issued to each of
          those outside directors who had served for the preceding year. No
          options have yet been officially issued under the plan, which expires
          January 27, 2007. However, the Company has outstanding obligations to
          issue options for 15,900 shares under this plan.

     (b   Restricted Stock Awards:

     .    As noted above, 600,000 shares of Common Stock have been reserved for
          issuance under the Precision Auto Care Stock Option and Restricted
          Stock Plan, adopted March 31, 1999. 131,125 shares are available for
          additional option grants and restricted stock awards under this plan,
          which expires March 31, 2009. To date the Company has awarded a total
          of 77,500 shares of restricted stock.
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August 3, 2000
Page 11

          Under the terms of each award, the right, title and interest to such
          shares will not vest until March 2002, unless the Company's share
          price reaches certain specified levels. To date 21,250 of the shares
          awarded have vested and certificates have been issued to the
          recipients.

     .    By private agreement in March 1999, the Company awarded 45,000 shares
          of restricted stock to its outside directors in lieu of cash fees owed
          to them. Under the terms of the award, the right, title and interest
          to such shares will not vest until March 2002, unless the Company's
          share price reached certain levels. To date 11,250 of the shares
          awarded have vested and certificates have been issued to the
          recipients.

     .    By private agreement in June 2000, the Company agreed to award 25,000
          shares of restricted stock to Arthur C. Kellar in connection with his
          agreement to amend an outstanding Subordinated Debenture. These shares
          have not yet been issued. In the same transaction the Company also
          agreed, that subject to shareholder approval, it would grant Mr.
          Kellar 25,000 shares of stock for each $100,000 drawn upon a letter of
          credit Mr. Kellar took out to support an appeal bond posted on behalf
          of the Company.