We didn't test the Range V8 product for fuel economy, although we have received feedback from a number of our users. Anecdotally, our users are reporting a +1 mpg to -1 mpg range when using the Range V8. Obviously, this depends on driving style, conditions, etc. We encourage you to do your own fuel economy testing and let us know the results.
Some of the things that can affect fuel mileage:
- Obviously, driving style and conditions. If you do mostly highway driving and then have a period where most of your driving is in town, then you will see mileage drop (sometimes fairly dramatically). If in addition you happen to spend all of your driving time in the regime where the factor AFM V4 mode is the most efficient (and the V8 disabler turns it off), you will see an additional hit to the mileage (usually around 1 mpg).
- Fuel type/formulation can affect mileage. Many parts of the country change additive and formulation depending on the season. Winter formulations usually contain more oxidizers and volatiles to aid in cold winter starting, which will hurt mileage (because of the reduced energy content).
- Outside weather conditions can affect mileage. Wind, rain, snow, cold temperatures can all affect how the engine management system manages the fuel and engine operation, sometimes cutting into fuel economy to maintain smooth operation.