Racing to work, to pick up your children from school, or go from one errand to the next not only wastes money and sends harmful emissions into the air, it barely saves you time, new research says. It is something to think about as gas prices stay elevated throughout the summer months and add pain to day-to-day driving and seasonal road tripping. Instead, abiding by posted speed limits can save U.S. drivers millions of dollars at the gas pump and eliminate millions of gallons of fuel each day, according to a study published Thursday in the Nature journal Communications Sustainability. That is fuel that, when burned, emits planet-warming gases into the atmosphere.