RIO VISTA GP LLC


                                VOTING AGREEMENT


                              ______________, 2004





                                VOTING AGREEMENT

     This  Voting  Agreement  (this  "AGREEMENT")  is  entered  into  as  of
____________,  2004, 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  the  signature  page  of  this  Agreement  (collectively, the "MEMBERS" and,
individually,  each  a  "MEMBER").  The Company, Penn Octane and the Members 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.
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                                    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 July 10, 2003, Penn Octane
granted  each  Member  the  right (the "PURCHASE RIGHT") to purchase twenty-five
percent  (25%) of the Penn Octane Interest at an exercise price equal to the pro
rata portion of the tax basis capital the Partnership (as defined in Section 1.4
of this Agreement) after the distribution of the common units of the Partnership
to  the  stockholders  of  Penn  Octane.

     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:

               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 (a) the sale, transfer, assignment,
pledge,  hypothecation  or  other  disposal  of  all  or any portion of  (i) 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"))  or  (b)  the merger, consolidation or sale of all or
substantially  all  of  the  assets  of the Partnership, its subsidiaries or the
Company.

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

3.   LEGEND.  Each certificate evidencing limited liability company interests in
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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 ______________, 2004, 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 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
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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 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  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.

     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.

                         (Signatures on following page.)



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

                                             SHORE CAPITAL LLC

                                             By:
                                                --------------------------------
                                                   Richard Shore, Jr., President


                                             -----------------------------------
                                             Jerome B. Richter


                      [Signature Page to Voting Agreement]