Superchips Mileage XS Fuel Economy Programmer Features - Improves fuel economy by up to 20 percent for diesel pickups and 10 percent for gasoline-powered cars and trucks. Calibrates your engine to run lower octane gas, when applicable. Adjusts your speedometer and odometer to compensate for non-stock tires and wheels. Retrieves and clears engine codes. Easy to update online. Superchips Mileage XS Fuel Economy Programmer. For the top selection of Superchips Performance Chips shop online today. The Superchips Mileage XS Fuel Economy Programmer will improve and personalize your vehicle. Power Programmers & Performance Tuners by Superchips - selected by many auto enthusiasts in the top automotive discussion forums. Superchips Mileage XS Fuel Economy Programmer for your vehicle will deliver the results you are looking for!