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                                                                    EXHIBIT 10.8

                                RIO VISTA GP LLC

                                VOTING AGREEMENT

                              ______________, 2003

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                                VOTING AGREEMENT

         This Voting Agreement (this "AGREEMENT") is entered into as of
____________, 2003, by and among Rio Vista GP LLC, a Delaware limited liability
company (the "COMPANY"), Penn Octane Corporation, a Delaware corporation and
member of the Company ("PENN OCTANE"), and the members of the Company identified
on signature page of this Agreement (collectively, the "MEMBERS" and,
individually, each a "MEMBER"). The Company, Penn Octane and the Investors are
sometimes referred to herein, collectively, as the "parties" and, individually,
as a "party" to this Agreement. Unless otherwise provided, capitalized terms
used in this Agreement have the meanings ascribed to them in Section 5 hereof.

                                    RECITALS

         WHEREAS, immediately prior to the date hereof, Penn Octane was the
owner of on hundred percent (100%) of the limited liability company interests of
the Company (the "PENN OCTANE INTEREST").

         WHEREAS, pursuant to option agreements dated _________, 2003, Penn
Octane granted each Member the right (the "PURCHASE RIGHT") to purchase
twenty-five percent (25%) of the Penn Octane Interest for $___________.

         WHEREAS, the exercise of the Purchase Right is conditioned upon the
execution and delivery of this Agreement by each Member.

                                    AGREEMENT

         NOW, THEREFORE, in consideration of the mutual promises,
representations, warranties, covenants, and conditions set forth in this
Agreement, the Purchase Right and for other good and valuable consideration, the
receipt and sufficiency of which is hereby acknowledged, the Parties hereby
agree as follows:

1.       VOTING AGREEMENT.

         1.1      Voting by Member for Managers. From and after the date hereof
and until the provisions of this Section 1 cease to be effective, at each
meeting of the members of the Company, or at any meeting of the members of the
Company at which members of the Board of Managers of the Company (the "BOARD")
are to be elected, or whenever members of the Board are to be elected by the
members of the Company by written consent, each Member agrees to vote or act
with respect to all of his, her or its limited liability company interests in
the Company and shall take all other necessary or desirable actions within such
Member's control whether in such capacity as a Member, manager of the Company,
officer of the Company, or otherwise (including, without limitation, attendance
at meetings, in person or by proxy, for purposes of obtaining a quorum and
execution of written consents), and the Company agrees to take all necessary and
desirable actions within its control, so as to:

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                  1.1.1    fix the number of members of the Board (the
"MANAGERS" and each, individually, a "MANAGER") at such number designated by
Penn Octane; and

                  1.1.2    elect each and every Manager designated by Penn
Octane.

         1.2      Removal and Substitution of Members of the Board. Each Member
agrees to vote or act with respect to all of his, her or its limited liability
company interests in the Company for the removal of any member of the Board upon
the request of Penn Octane and for the election to the Board of a substitute
nominated by Penn Octane in accordance with the provisions of Section 1.1. Each
Member agrees that no Manager may be removed from office without the approval of
Penn Octane. Each Member further agrees to vote or act with respect to all of
his, her or its limited liability company interests in the Company in such
manner as shall be necessary or appropriate to ensure that any vacancy on the
Board occurring for any reason shall be filled only in accordance with the
provisions of Section 1.1.

         1.3      Voting by Member on All Other Matters. From and after the date
hereof and until the provisions of this Section 1 cease to be effective, at each
meeting of the members of the Company, or whenever members of the Company are to
take action by written consent, each Member agrees to vote or act with respect
to all of his, her or its limited liability company interests in the Company as
directed by Penn Octane and shall take all other necessary or desirable actions
within such Member's control whether in such capacity as a Member, Manager,
officer of the Company, or otherwise (including, without limitation, attendance
at meetings, in person or by proxy, for purposes of obtaining a quorum and
execution of written consents), and the Company agrees to take all necessary and
desirable actions within its control, as directed by Penn Octane.

         1.4      Exceptions. The provisions of Section 1.3 of this Agreement do
not apply with respect to any matter involving the sale, transfer, assignment,
pledge, hypothecation or other disposal of all or any portion of any general
partner interest (the "GENERAL PARTNER INTEREST") in Rio Vista Energy Partners
L.P., a Delaware limited partnership (the "PARTNERSHIP"), or (ii) any Incentive
Distribution Rights (as defined in the First Amended and Restated Agreement of
Limited Partnership of Rio Vista Energy Partners L.P. (the "PARTNERSHIP
AGREEMENT")).

2.       NO REVOCATION. The voting agreements contained herein are coupled with
an interest and may not be revoked during the term of this Agreement.

3.       LEGEND. Each certificate evidencing limited liability company interests
in the Company and each certificate issued in exchange for or upon the Transfer,
as defined in Section 5 below, of any limited liability company interests of the
Company will be stamped or otherwise imprinted with a legend in substantially
the following form:

                  "THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE
                  SUBJECT TO A VOTING AGREEMENT DATED AS OF
                  ______________, 2003, ENTERED INTO BY AND AMONG THE
                  COMPANY, PENN OCTANE AND CERTAIN OF THE COMPANY'S
                  MEMBERS, AND BY ACCEPTING THESE SECURITIES, THE
                  PERSON ACCEPTING SUCH INTEREST SHALL BE DEEMED TO

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                  AGREE TO AND SHALL BECOME BOUND BY ALL THE
                  PROVISIONS OF SAID VOTING AGREEMENT. A COPY OF SUCH
                  VOTING AGREEMENT WILL BE FURNISHED, WITHOUT CHARGE,
                  BY THE COMPANY TO THE HOLDER HEREOF UPON WRITTEN
                  REQUEST."

The Company will imprint such legend on all certificates representing limited
liability company interests outstanding prior to the date hereof.

4.       TRANSFER. Prior to any Transfer of any limited liability company
interest in the Company or any interest therein to any Person, which Transfer is
subject to the restrictions set forth in the Agreements, the Member effecting
such Transfer will cause the prospective Transferee(s) to execute and deliver to
each Party a counterpart of this Agreement.

5.       DEFINITIONS. As used in this Agreement, the following terms shall have
the meanings set forth below:

         5.1      "PERSON" means an individual, a partnership, a corporation, a
limited liability company, an association, a joint stock company, a trust, a
joint venture, an unincorporated organization, and a governmental entity or any
department, agency, or political subdivision thereof.

         5.2      "TRANSFER" means the sale, transfer, assignment, pledge,
hypothecation or other disposal.

         5.3      "TRANSFEREE" shall mean the recipient of a transfer.

6.       MISCELLANEOUS.

         6.1      Notices. All notices and other communications required or
permitted hereunder shall be in writing and shall be mailed by registered or
certified mail, postage prepaid, sent by facsimile or electronic mail or
otherwise delivered by hand or by messenger addressed as follows:

                           (1)      if to a Member or Penn Octane, at the
Member's or Penn Octane's, as applicable, address, facsimile number or
electronic mail address as shown in the Company's records, as may be updated in
accordance with the provisions hereof.

                           (2)      if to the Company, one copy should be sent
to its address or facsimile number set forth on the signature page of this
Agreement and addressed to the attention of the President, or at such other
address or facsimile number as the Company shall have furnished to the Members.

Each such notice or other communication shall for all purposes of this Agreement
be treated as effective or having been given when delivered if delivered
personally, or, if sent by mail, at the earlier of its receipt or 72 hours after
the same has been deposited in a regularly maintained

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receptacle for the deposit of the United States mail, addressed and mailed as
aforesaid or, if sent by facsimile, upon confirmation of facsimile transfer.

         6.2      Successors and Assigns. Except as otherwise provided herein,
the terms and conditions of this Agreement shall inure to the benefit of and be
binding upon the respective successors and assigns of the parties. Nothing in
this Agreement, express or implied, is intended to confer upon any party other
than the parties hereto or their respective successors and assigns any rights,
remedies, obligations or liabilities under or by reason of this Agreement,
except as expressly provided in this Agreement.

         6.3      Severability. In the event that any provision of this
Agreement becomes or is declared by a court of competent jurisdiction to be
illegal, unenforceable or void, this Agreement shall continue in full force and
effect without said provision, and the parties agree to negotiate, in good
faith, a legal and enforceable substitute provision which most nearly effects
the parties' intent in entering into this Agreement.

         6.4      Amendments and Waivers. Any term of this Agreement may be
amended and the observance of any term of this Agreement may be waived (either
generally or in a particular instance and either retroactively or
prospectively), only with the written consent of (i) the Company, (ii) each
Member and (iii) Penn Octane. Any such amendment, waiver, discharge or
termination effected in accordance with this paragraph shall be binding upon
each holder of any securities purchased under this Agreement at the time
outstanding (including securities into which such securities have been converted
or exchanged or for which such securities have been exercised) and each future
holder of all such securities.

         6.5      Governing Law. This Agreement shall be governed by and
construed under the laws of the State of Delaware as applied to agreements among
Delaware residents entered into and to be performed entirely within Delaware.

         6.6      Specific Performance. The rights of the parties under this
Agreement are unique and, accordingly, the parties shall, in addition to such
other remedies as may be available to any of them at law or in equity, have the
right to enforce their rights hereunder by actions for specific performance to
the extent permitted by law.

         6.7      Counterparts. This Agreement may be executed in any number of
counterparts, each of which, when so executed and delivered, will be deemed an
original, and all such counterparts together will constitute one and the same
instrument.

         6.8      Conflict. In the event of any conflict between the terms of
this Agreement and the Company's Limited Liability Company Agreement, the
Partnership Agreement or any other agreement to which the Company, Penn Octane
or a Member is bound, the terms of this Agreement will control.

         6.9      Attorney's Fees. In the event that any suit or action is
instituted to enforce any provision in this Agreement, the prevailing party in
such dispute shall be entitled to recover from the losing party all fees, costs
and expenses of enforcing any right of such prevailing party under or with
respect to this Agreement, including without limitation, such reasonable fees
and
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expenses of attorneys and accountants, which shall include, without limitation,
all fees, costs and expenses of appeals.

         6.10     Titles and Subtitles. The titles and subtitles used in this
Agreement are used for convenience only and are not to be considered in
construing or interpreting this Agreement. All references in this Agreement to
sections, paragraphs, exhibits and schedules shall, unless otherwise provided,
refer to sections and paragraphs hereof and exhibits and schedules attached
hereto.

         6.11     Entire Agreement. This Agreement constitutes the full and
entire understanding and agreement among the parties with regard to the subject
matter hereof and supercedes and replaces any prior verbal or written
understandings, communications, or representations between the Parties in
relation to the subject matter of this Agreement.

         6.12     Construction. The parties hereto have participated jointly in
the negotiation and drafting of this Agreement. In the event an ambiguity or
question of intent or interpretation arises, this Agreement shall be construed
as if drafted jointly by the parties hereto and no presumption or burden of
proof shall arise favoring or disfavoring any party hereto by virtue of the
authorship of any of the provisions of this Agreement. Any reference to any
federal, state, local, or foreign statute or law shall be deemed also to refer
to all rules and regulations promulgated thereunder, unless the context requires
otherwise.

         6.13     Delays or Omissions. Except as expressly provided herein, no
delay or omission to exercise any right, power or remedy accruing to any party
to this Agreement upon any breach or default of any other party under this
Agreement shall impair any such right, power or remedy of such non-defaulting
party, nor shall it be construed to be a waiver of any such breach or default,
or an acquiescence therein, or of or in any similar breach or default thereafter
occurring, nor shall any waiver of any single breach or default be deemed a
waiver of any other breach or default theretofore or thereafter occurring. Any
waiver, permit, consent or approval of any kind or character on the part of any
party of any breach or default under this Agreement, or any waiver on the part
of any party of any provisions or conditions of this Agreement, must be in
writing and shall be effective only to the extent specifically set forth in such
writing. All remedies, either under this Agreement or by law or otherwise
afforded to any party to this Agreement, shall be cumulative and not
alternative.

         6.14     Telecopy Execution and Delivery. A facsimile, telecopy or
other reproduction of this Agreement may be executed by one or more parties
hereto, and an executed copy of this Agreement may be delivered by one or more
parties hereto by facsimile or similar electronic transmission device pursuant
to which the signature of or on behalf of such party can be seen, and such
execution and delivery shall be considered valid, binding and effective for all
purposes. At the request of any party hereto, all parties hereto agree to
execute an original of this Agreement as well as any facsimile, telecopy or
other reproduction hereof.

         6.15     Jurisdiction; Venue. With respect to any disputes arising out
of or related to this Agreement, the parties consent to the exclusive
jurisdiction of, and venue in, the state or federal courts in Harris County in
the State of Texas.

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         6.16     Jury Trial. EACH OF THE PARTIES HERETO HEREBY IRREVOCABLY
WAIVES, TO THE FULLEST EXTENT PERMITTED BY LAW, ANY AND ALL RIGHT TO TRIAL BY
JURY IN ANY LEGAL PROCEEDING (WHETHER SOUNDING IN CONTRACT, TORT OR OTHERWISE)
ARISING OUT OF OR RELATED TO THIS AGREEMENT.

         6.17     Further Assurances; Instruments. Each of the Members, Penn
Octane and the Company agree not to vote any of their respective limited
liability interests in the Company, or to take any other actions, that would in
any manner defeat, impair, be inconsistent with or adversely affect the rights
of the parties under Section 1 of this Agreement. From time to time, each party
hereto shall execute and deliver such instruments and documents as may be
reasonably necessary to carry out the purposes and intent of this Agreement.

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         IN WITNESS WHEREOF, the undersigned or each of their respective duly
authorized officers or representatives have set their hands hereunto effective
upon the date first above written.

COMPANY:                                   PENN OCTANE:

RIO VISTA GP LLC                           PENN OCTANE CORPORATION
a Delaware limited liability company       a Delaware corporation

By: ________________________________
         Richard Shore, Jr.                By: _________________________________
         President                                  Jerome B. Richter
820 Gessner Road                                    Chief Executive Officer
Suite 1250
Houston, Texas 77024                       THE MEMBERS:

                                           SHORE CAPITAL LLC

                                           By: _________________________________
                                                 Richard Shore, Jr., President

                                           _____________________________________
                                           Jerome B. Richter

                      [Signature Page to Voting Agreement]