The RaceME, RaceME Pro & RaceME Ultra have all been engineered to maximize fuel efficiency. Late Injection events (post injection) are disabled for improved fuel economy. Injection timing is optimized to achieve the best fuel mileage. Regeneration has also been deactivated. These three things allow instantly improve fuel mileage. But the single biggest contributing factor to better fuel mileage is the fact that your removing a huge restriction in the exhaust system by deleting the DPF. On average we see fuel mileage increases around 3-4mpg. However, fuel mileage can vary. Driving habits, tire size, vehicle condition, etc. can effect these numbers. For example: If you were to delete the DPF on a brand new truck the increase in mileage would be minimal. The reason being; the CAT & DPF haven't plugged up with soot yet. In most cases when the DPF is plugged our customers are getting 13-14mpg or worse. When the DPF is deleted; combined mileage is around 18mpg. So depending how bad your mileage is to begin with you could see substantial gains. Deleting the DPF with a RaceME tuner not only gives you better fuel mileage but you also get the added benefits of reduced EGT's, quicker turbo response and a more reliable truck in general.