In the process of modifying my JK, each step has lowered the mpg like I thought it would. The 34" tires droped it from 19+ to a little less than 18. I corrected the speedo with the Flashpaq and set it to 87 performance. Another slight drop in economy. Last week it was regeared to 513s and on the way home after resetting the gauge was trying to settle in at 16.8. Last night I reflashed it to the economy mode and on the way into the office (20 miles of highway @60 mph) it kept dropping to about 15.5. Now, I know that isn't 100% accurate, but it indicates a general trend. Many on this forum say their mpg went up when the regeared. Mine definitely went down. Overall, I've dropped 4 mpg by lifting it 3", adding 34" tires and regearing to 513s. The bumpers will arrive today and add another 275#s of weight. Am I the only one to get these kind of results? It's pretty much what I would have expected, but was encouraged by others saying their economy improved. I don't expect a built Jeep to be an economy ride, but with gearing it up into a better torque range, it should improve. Again, am I the only one??

 

07 Rubi Unlimited auto w/ 3" 33s bumpers, winch, hardtop, CAI and I run 15 around town and 16 on the highway.

 

Mine gets about 15.2 mpg. It was getting almost 17 before I swapped the front bumper. I got the 33's, 4.10 gears, and 4 inch lift.

 

I get between 12-15 mpg. Traffic moves fast up here.

 

Stop me if I'm wrong here... regearing gives you power to turn your larger tires but also puts your revs up. Though the engine is working under less load, the higher revs will still burn more fuel.
Stop me if I'm wrong.

My flashpac hasn't yielded the mpg increase i was hoping for (I haven't suffered any either). ubt the Jeep is much crisper at the throttle and the shift points are better.
I had to set it back to stock last week for an auto tranny cooler overheat recall and it was a slug to drive that day. The 87 tune went right back on when I got it back.

 

Heh, mine gets 16mpg if I'm lucky, and the damn things stock.

 

Really? Im getting almost 22mpg acording to the computer. I know its higher then reality, but my old dodge truck was only off 1.3-1.5 mpg on the computer.

Bone stock other then flat flares.

 

Something sounds wrong here then.

I'm running 35s w/ 3 inches, and getting about 15.5-16 MPG. Shifting at 2k RPMS.

Obviously your added weight is not going to help by putting the bumpers on.

 

2dr 6 spd '09 JK; heavy bumpers and side rails + CAI, cat-back and Superchips programmed for hi-octane and performance; stock wheels/tires and no lift. I get 15 1/2 when I put my foot in it! about 17 if I don't - and on some freeway runs about 18 1/2 (+ or -). Hope this helps

 

So far, it sounds like it's par for the course. It follows everything I have done to vehicles in the past. Change it from stock and the economy goes down hill. My ZJ went from 18+ to 14 by the time it was built, so I shouldn't be surprized. I may play around with the shocks to get a smoother ride, but I think the MTRs w/kevlar are a rougher rolling tire and I can't do much about them.