ENERGY

Cars Using Natural Gas Run Cleaner, Study Says: A study to be released today by the Gas Research Institute concludes that vehicles running on compressed natural gas emit far fewer pollutants than the same vehicles using either regular gasoline or lower-emission reformulated gasolines. The study, prepared for the industry-backed institute by the Southwest Research Institute in Austin, Tex., found that a GMC Sierra 1500 truck engine produced less pollutants than the same engine using the more conventional fuels. The gas institute said its study is the first to directly compare the emissions of natural gas with those from the liquid fuels.