Rticul8

About 2 weeks ago I purchased a 2015 Jeep Wrangler Sport 2 door 6 speed with 3.73 gears. Drove it 300 miles home from Houston to McAllen Texas. It did like 19mpg with 29s ( awesome exactly what I was expecting ). I installed some 285/75/16 duratracs and 16in level 8 zx wheels with no lift. This last tank, driving like a grandpa, 90% city driving I got like 14 mpg. Now before ya'll hang me, I know its a jeep and it sucks on gas. I sold a 98 tj that did 12mpg to buy this, and have owned XJ, MJ in the past too.

My question is, Does it get better after a certain amount of miles? I know these new motors are very intelligent and adjust to suit the driver needs.
I have read posts that say that the 3.6l gets better after 2500 mile internal computer break in. Am I condemning myself by driving like a grandpa and early shifting during this period? If my questions are stupid, I apologize. I was dropped as a baby.

My Speedo is 5 mph off at 70 ( read 65) . So I added like 10 miles to my hand calculations to get the 14.

Rob 12B1P

14 isnt bad for City.

Rticul8

With no added extra weight? and a 6 speed? ive read people get closer to 17 with my setup

Evangelos k

What's the logic behind 10 miles?
It seems your speedo is about 7.2% off, and that's what you should add to you calculations for mileage.

A tire size calculator will let you know exactly the % difference between old and new set up , and you can adjust accordingly.

Rticul8

Honestly I just guesstimated lol

None the less by the percentage you provided in 120 miles its 8.64 miles. Which is close to the 10 I added. I calculated it using 130 when my trip recorded 120.

Strider

Bite the bullet and buy something like a Pro-Cal and recal your speedo. You can't calculate for the mph very accurately without resetting your speedo. I have the same set-up as you do, Man with 3.73 and 32.25 in tires. If I drive like the old man I am (60 mph on freeway) I'll get 20.5 mpg calculated by dividing miles driven by gallons used. Don't trust the Jeeps Mpg calculator. My 15 motor is still a little tight, I only have 4000 mi on it.

snowride20

http://tire-size-conversion.com/tire-size-calculator/ Try this link for some answers. I did almost the same tire swap as you did and found myself about 10% off. I figured adding 10% to the gas mileage should get me close to accurate. My 2013 JKU was getting 18 mpg till I went to 35's.

Rticul8

i definitely do not rely on my jeeps mpg calc. I am doing it manually. I think it mainly has to do that i drive like 7 miles to work and by the time the motor is actually heating up i already got to work. Was still expecting better than what i am getting with 8.8 gallons i got about 130 miles :(

SF_E60

I have a 2012 JK 6speed w/35k and I'm getting about 19.9-20.1mpg bone stock. I work 12 miles from home mostly all freeway. I haven't done any city driving since I really don't drive in the city much.

mhockey9090

I drive almost 6 miles to work everyday and get roughly 15mpg with 35s and re geared to 4.88s. Even before the re gear i was getting maybe 15.4 idk. So its not far off and im all city