Four companies announced plans this week to develop market research on the national gas vehicle industry and to establish a joint venture that will establish public and private natural gas fueling stations.

The consortium is composed of Natural Fuels Corp. of Denver, the nation's first full-service natural gas transportation fuel company and three Houston companies: Entex Corp, Houston Pipe Line Co., and The Vista Group Inc., an investment firm."The time for alternative fuels has arrived. We Americans need to rely on our natural gas resources combined with energy conservation ideas to produce clean air," said Thomas Y. Hamilton, Vista Group spokesman. "We are fortunate to be joining with the consortium to fast-track Houston as the ideal place for leadership in alternative fuels."

Texas Land Commissioner Garry Mauro called the consortium "a bold industry statement" favoring clean-air legislation a-dopted in 1989 by the Texas Legislature.

The legislation requires certain school district, transit authority and state agency vehicles to operate on alternative fuels beginning September 1991.

"The consortium is committed to meeting the needs of fleet operators who are affected by the Texas Plan and federal clean air legislation," said Paul Nelson, con-sortium spokesman and Natural Fuels Corp. vice president.

"We are confident the research and planning will prove positive for the consortium members."