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 development of oil and gas in Oklahoma and the terminalling and transportation of bulk chemical and petroleum products in Virginia, today announced its financial results for the year ended December 31, 2007. The Company reported a net loss of ($4.9) million or ($2.44) per common unit. �2007 was a transitional year in which we divested the Company of non-core assets and acquired the operations of Regional and certain assets in Oklahoma,� said Ian Bothwell, Chief Executive Officer of Rio Vista Energy Partners. �Although the 2007 operating results reflect the expenses associated with being a public company, divesting legacy businesses and acquiring oil and gas assets, we believe these costs will be supported by increased production levels in 2008.� The following table summarizes the results of operations from continuing operations for the year ended December 31,2007 and reflects the results associated with the Transportation and Terminaling Business associated with bulk and petroleum products associated with Regional operations and LPG (sold December 31, 2007) including all costs associated with operation of the US-Mexico Pipelines and Matamoros Terminal Facility, and the acquisition of the Oklahoma assets during November 2007 and all indirect income and expenses of Rio Vista. YEAR ENDED DECEMBER 31, 2007 Oklahoma Regional LPG Corporate/ � Assets (a) Enterprises (b) Transportation (c) Other Total � Revenues 527,000 3,038,000 2,341,000 - 5,906,000 Cost Of Goods Sold 390,000 2,399,000 1,971,000 - 4,760,000 Gross Profit 137,000 639,000 370,000 - 1,146,000 Selling, General And Adminis-trative Expenses 41,000 363,000 258,000 4,023,000 4,685,000 Loss on sale of remaining LPG assets - - 406,000 - 406,000 Operating Income 96,000 276,000 (294,000) (4,023,000) (3,945,000) Other Income (Expense) Interest Expense (275,000) (431,000) (281,000) (7,000) (994,000) Interest Income - 14,000 1,000 2,000 17,000 � � � � � Income From Continuing Operations Before Taxes (179,000) (141,000) (574,000) (4,028,000) (4,922,000) Provision For Income Taxes (4,000) (51,000) 34,000 - � (21,000) Income (loss) From Contin-uing Operations (175,000) (90,000) (608,000) (4,028,000) (4,901,000) � (a) Acquired during November 2007 (b) Acquired during July 2007 (c) Business commenced in August 2006 and sold December 31, 2007 Audit Opinion Going Concern Qualification The independent auditor�s opinion included in Rio Vista�s financial statements for the year ended December 31, 2007 included in its Form 10-K filed on April 15, 2008 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; 2) the pledge of substantially all the Rio Vista�s assets as collateral on existing debt, which may render Rio Vista unable to obtain additional financing collateralized by those assets; and 3) Rio Vista�s deficit in working capital. For further information, please refer to Rio Vista�s Form 10-K filed with the SEC on April 15, 2008 (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 acquisition of the properties in East Central Oklahoma may not prove successful and has substantially increased Rio Vista�s and its subsidiaries� indebtedness and contingent liabilities, and may present integration difficulties. Continuation and expansion of production may require unforeseen capital investment. Future production may be lower than anticipated, and actual natural gas reserves may prove lower than estimated. If Rio Vista does not receive sufficient revenues from the use of its assets, Rio Vista would suffer material adverse consequences to its business, resulting Rio Vista�s inability to meet its debt obligations when due and reduced cash available for distributions. Rio Vista�s credit facility with TCW prohibits distributions by Rio Vista�s Oklahoma subsidiaries during the first 12 months of the credit facility and limits those distributions to 75% of defined available cash flow thereafter. As a result, Rio Vista may not have sufficient available cash to pay its required debt obligations and/or minimum quarterly distributions. In addition, Rio Vista may not distribute sufficient cash to meet the tax obligations of unitholders associated with the ownership of common units. If Rio Vista does not have sufficient capital resources for acquisitions or opportunities for expansion, 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.