I have a 2012 JK unlimited Rubicon with 31" BFG, auto with 3.73 and was getting 17 mpg in the city, and pretty happy with the performance. Now I'm running a 6" teraflex long arm with 38"x13.5x18" my performance is almost like stock but my mileage is around 14-16 mpg. I lost a little in the MPG...