ExxonMobil Corp. has joined a group of powerful auto manufacturers, energy companies, and government agencies studying fuel cell vehicles in California. Considered by some to be the least environmentally sensitive of the major oil companies, ExxonMobil’s decision to align itself with the California Partnership marks its latest effort to stay involved in what may be the biggest development in the energy business. ExxonMobil already has a research partnership with both General Motors Corp. and Toyota Motor Corp. to research fuel cell vehicles. In those partnerships, ExxonMobil is developing a so-called gasoline predecessor for the fuel cells, raising the possibility that gasoline could still be used in automobiles that use fuel cells. That would keep in place the current gasoline station network, which the industry has spent years and countless amounts of money constructing, and keep oil companies at the center of fuel marketing. “Gasoline fuels for fuel cell vehicles offer the advantage of using an existing and familiar infrastructure that has been fine-tuned over 100 years,” said Bill Innes, president of ExxonMobil Research and Engineering Co. in a statement on the company’s decision to join the California Partnership. “The fuel aspect of the fuel cell vehicle plays a crucial role for the successful deployment of this technology and its acceptance by the consumer,” he added. ExxonMobil is hoping to bring the gasoline processor technology to the California Partnership, a group that began work in 1999 with the aim of exploring the use of fuel cell cars, buses, and trucks in California. The group includes auto manufacturers such as DaimlerChrysler and Ford Motor Co., energy companies such as BP Amoco, fuel cell companies such as Ballard Power Systems Inc., and government agencies ranging from the California Air Resources Board to the U.S. Department of Energy.