RVEP Rio Vista Energy Partners L.P. (MM)

Rio Vista Energy Partners L.P. (�Rio Vista�) (NASDAQ: RVEP), an energy services master limited partnership focused on the terminalling and transportation of bulk chemical and petroleum products in Virginia and the development of oil and gas in Oklahoma, today announced its financial results for the year ended December 31, 2008. The Company reported a net loss of ($6.2) million or ($2.34) per common unit.

The following table summarizes the results of operations from continuing operations for the year ended December 31, 2008 and reflects the results associated with i.) the Transportation and Terminalling Business associated with bulk and petroleum products associated with Regional operations (acquired during July 2007) and LPG (commenced during August 2006 and was sold on December 31, 2007), (including all costs associated with operation of the US-Mexico Pipelines and Matamoros Terminal Facility), ii.) the operation of the Oklahoma Assets, which was acquired during November 2007 and iii.) all indirect income and expenses of Rio Vista.

Because of the commencement and sale of our LPG Transportation business during August 2006 and December 2007, respectively, and our rapid growth through the acquisitions of Regional and the Oklahoma Assets during 2007, our historical results of operations and period-to-period comparisons of these results during the years ended 2007 and 2008 are not that meaningful or indicative of future results.

YEAR ENDED DECEMBER 31, 2008 � � � � � Oklahoma Regional LPG Corporate/ Assets (a) � Enterprises (b) � Transportation (c) � Other Total � Revenues $ 5,247,000 $ 8,573,000 $ - $ 1,000 $ 13,821,000 Cost Of Goods Sold � 4,322,000 � � � 6,444,000 � � � - � � � (8,000 ) � 10,758,000 � Gross Profit 925,000 2,129,000 - 9,000 3,063,000

Selling, General And Administrative Expenses

493,000 1,167,000 - 3,650,000 5,310,000

Loss on sale of remaining LPG � related assets

� - � � � - � � � 351,000 � � � - � � 351,000 � Operating Income 432,000 962,000 (351,000 ) (3,641,000 ) (2,598,000 ) Other Income (Expense) Interest Expense (2,849,000 ) (631,000 ) - (178,000 ) (3,658,000 ) Interest Income � 7,000 � � � - � � � - � � � 1,000 � � 8,000 � �

Income (loss) from Continuing Operations Before Taxes

(2,410,000 ) 331,000 (351,000 ) (3,818,000 ) (6,248,000 )

Provision (Benefit) For Income Taxes

� (103,000 ) � � 66,000 � � � - � � � - � � (37,000 )

Income (loss) From Continuing Operations

$ (2,307,000 ) � $ 265,000 � � $ (351,000 ) � $ (3,818,000 ) $ (6,211,000 )

�

�

� � YEAR ENDED DECEMBER 31, 2007 � Oklahoma Regional LPG Corporate/ Assets (a) � Enterprises (b) � Transportation (c) � Other Total � Revenues $ 528,000 $ 3,038,000 $ 2,341,000 $ - $ 5,906,000 Cost Of Goods Sold � 390,000 � � � 2,399,000 � � � 1,971,000 � � � 45,000 � � 4,805,000 � Gross Profit 137,000 639,000 370,000 (45,000 ) 1,101,000

Selling, General and Administrative Expenses

41,000 363,000 258,000 4,008,000 4,670,000

Loss on sale of remaining LPG � related assets

� - � � � - � � � 406,000 � � � - � � 406,000 � Operating Income (loss) 96,000 276,000 (294,000 ) (4,053,000 ) (3,975,000 ) Other Income (Expense) Interest Expense (275,000 ) (322,000 ) (281,000 ) (7,000 ) (885,000 ) Interest Income � - � � � 14,000 � � � 1,000 � � � 2,000 � � 17,000 �

Loss From Continuing Operations Before Taxes

(179,000 ) (32,000 ) (574,000 ) (4,058,000 ) (4,843,000 )

Provision (Benefit) For Income Taxes

� (4,000 ) � � (51,000 ) � � 34,000 � � � - � � � (21,000 )

Income (loss) From Continuing Operations

$ (175,000 ) � $ 19,000 � � $ (608,000 ) � $ (4,058,000 ) $ (4,822,000 ) � � CHANGES YEAR ENDED DECEMBER 31, 2008 COMPARED WITH YEAR ENDED DECEMBER 31, 2007 � � � � � Oklahoma Regional LPG Corporate/ Assets (a) � Enterprises (b) � Transportation (c) � Other Total � Revenues $ 4,720,000 $ 5,535,000 $ (2,341,000 ) $ 1,000 $ 7,915,000 Cost Of Goods Sold � 3,932,000 � � � 4,045,000 � � � (1,971,000 ) � � (53,000 ) � 5,953,000 � Gross Profit 788,000 1,490,000 (370,000 ) 54,000 1,962,000

Selling, General And Administrative Expenses

452,000 804,000 (258,000 ) (358,000 ) 640,000

Loss on sale of remaining LPG � related assets

� - � � � - � � � (55,000 ) � � - � � (55,000 ) Operating Income (Loss) 336,000 686,000 (57,000 ) 412,000 1,377,000 Other Income (Expense) Interest Expense (2,574,000 ) (309,000 ) 281,000 (171,000 ) (2,773,000 ) Interest Income � 7,000 � � � (14,000 ) � � (1,000 ) � � (1,000 ) � (9,000 )

Income (loss) From Continuing Operations Before Taxes

(2,231,000 ) 363,000 223,000 240,000 (1,405,000 )

Provision (Benefit) For Income Taxes

� (99,000 ) � � 117,000 � � � (34,000 ) � � - � � � (16,000 )

�

Income (loss) From Continuing Operations

$ (2,132,000 ) � $ 246,000 � �

$

257,000

� �

$

240,000

� $ (1,389,000 ) �

�

(a) Acquired during November 2007(b) Acquired during July 2007(c) Business commenced in August 2006 and sold December 31, 2007

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Year Ended December 31, 2008 Compared With Year Ended December 31, 2007

Revenues. Revenues for the year ended December 31, 2008 were $13.8 million and includes the results of Regional and the Oklahoma Assets for the twelve months during 2008. Revenues during the year ended December 31, 2007 were $5.9 million and includes the results of Regional for the period July 28, 2007 to December 31, 2007, the results of the Oklahoma Assets for the period November 19, 2007 to December 31, 2007 and the results of the LPG transportation for the full twelve months. The results for the two periods are not comparative since each period contains different business operations for different periods of time.

Cost of goods sold. Cost of goods sold for the year ended December 31, 2008 was $10.8 million and includes the results of Regional and the Oklahoma Assets for the twelve months during 2008. Cost of goods sold during the year ended December 31, 2007 were $4.8 million and includes the costs of goods sold of Regional for the period July 28, 2007 to December 31, 2007, the cost of goods sold of the Oklahoma Assets for the period November 19, 2007 to December 31, 2007 and the cost of goods sold of the LPG transportation for the full twelve months. The results for the two periods are not comparative since each period contains different business operations for different periods of time.

Selling, general and administrative expenses. Selling, general and administrative expenses were $5.3 million for the year ended December 31, 2008. Excluding the selling, general and administrative expenses associated with the acquisitions or sales of Regional, the Oklahoma Assets and/or the LPG Transportation business, the remaining selling, general and administrative expenses were associated with corporate related activities. These selling, general and administrative costs were $3.6 million during the year ended December 31, 2008 compared with $4.0 million during the year ended December 31, 2007. These costs were comprised of indirect selling, general and administrative expenses directly incurred by Rio Vista or allocated by Penn Octane to Rio Vista in accordance with the Omnibus Agreement. The costs consisted of salary related costs, legal, accounting and other professional fees, and other corporate related costs, including insurance, taxes other than income, and public company expenses. Salary related costs allocated by Penn Octane were based on the percentage of time spent by those employees (including executive officers) in performing Rio Vista related matters compared with the overall time spent working by those employees.

Audit Opinion Going Concern Qualification

The independent auditor�s opinion included in Rio Vista�s financial statements for the year ended December 31, 2008 included in its Form 10-K filed on April 14, 2009 with the Securities and Exchange Commission (�SEC�) contained a �going concern� qualification. The qualification states that �conditions exist which raise substantial doubt about Rio Vista�s ability to continue as a going concern.� Factors contributing to the inclusion of the qualification include: 1) concern over Rio Vista�s ability to generate sufficient cash flow in the future to pay its expenses and its current debt obligations as they become due and 2) Rio Vista�s dependence on Penn Octane Corporation, the parent of Rio Vista�s general partner, to continue as a going concern. For further information, please refer to Rio Vista�s Form 10-K filed with the SEC on April 14, 2009 (SEC file number 000-50394).

About Rio Vista Energy Partners L.P.

Rio Vista is a master limited partnership focused on acquiring and developing oil and gas exploration, production and transportation assets. Through its subsidiaries, Rio Vista currently owns certain leasehold interests of oil and gas producing properties and associated pipeline gathering systems in East Central Oklahoma. Rio Vista is also engaged in liquid bulk storage, transloading and transportation of chemicals and petroleum products through its assets and operations in Hopewell, Virginia. Rio Vista seeks to grow primarily through the acquisition of qualified oil and gas assets. Penn Octane Corporation (OTCBB: POCC) owns 75% of Rio Vista GP LLC, the general partner of Rio Vista.

Forward-Looking Statements

Certain of the statements in this news release are forward-looking statements, including statements regarding the ability of Rio Vista to continue as a going concern. Although these statements reflect Rio Vista's beliefs, they are subject to uncertainties and risks that could cause actual results to differ materially from expectations. The ability of Rio Vista to extend, defer and/or restructure its current debt obligations is uncertain. Continuation and expansion of its oil and gas properties requires additional capital investment which Rio Vista has been unable thus far to obtain. Future production may be lower than anticipated and actual natural gas reserves may prove lower than estimated. Revenues from the operations in Hopewell, Virginia may be lower than anticipated. If Rio Vista is unable to extend, defer and/or restructure its debt obligations, Rio Vista would suffer material adverse consequences to its business, resulting Rio Vista�s inability to meet its debt obligations when due, and Rio Vista�s creditors may foreclose on those assets which are held as collateral against those debt obligations. In addition, Rio Vista may not generate sufficient cash to meet other obligations, including operating expenses, distributions to unitholders and other capital required to make additional acquisitions or to develop opportunities for expansion. As a result, Rio Vista�s growth will be limited. Rio Vista may be unable to complete future acquisitions of qualified oil and gas assets or other transactions and, even if completed, acquisitions may not prove successful. Additional information regarding risks affecting Rio Vista's business may be found in Rio Vista's most recent reports on Form 8-K, Form 10-Q and Form 10-K and its registration statement on Form 10 and in Penn Octane Corporation�s most recent reports on Form 8-K, Form 10 Q and Form 10-K filed with the Securities and Exchange Commission.