The system is already in use by eight railroads on 2,500 locomotives in North America, Australia and Brazil. Customers have seen fuel savings of 3% to 17%, depending on the type of train service and topography, GE says. The company says locomotives equipped with Trip Optimizer have already logged 100,000,000 real-world miles, saving some 25 million gallons of diesel fuel. Norfolk Southern estimates that an increase in network velocity of just one mile per hour will save the company over $200 million a year.