Tuner Superchips offers an all-new Mileage XS Diesel treatment, engineered exclusively for fuel savings in full-size diesel pickup trucks. The Mileage XS targets five key areas to optimize the entire rpm band: fuel injection and ignition, throttle-position optimization, displacement on demand, transmission shifting, and torque-converter strategies. With these five targets, Superchips claims up to 20-percent-better fuel economy. Retail price: $300.