Freightliner has a National hot line manned 24 hours a day.You can call them at 1-800-385-4357,give them the last 6 digits of your vin number and they can tell you everything about the truck.They can also help with technical assistance. As far as mileage goes that can be all over the place,depending on your engine and how you drive. I have a FL 70 with the Cummins C 8.3 and I average about 10.5 - 11 MPG,sometimes it gets up to 12,sometimes based on winds and loads it drops to 9.