You will see your best mileage around 55-60mph. Tucking behind a semi speed regulated at 62 or 63mph makes it easy

 

So you're saying the mpg is better at 55-60 mph than it would be a 45 mph?

 

LOL, dont even think about going bigger on tires if mpg worries you.

 

With the 4.10 and stock tires i was right at 17.5. I put on 35s at 1k miles. On the same commute, no interstate 55mph, I get around 18.3. Interstate MPG is worse with the 35s. Yes, I get better MPG at 55 than I do at 45 because of the overdrive

 

That's strange, because I get better mpg's the slower I go, down to about 35 mph.
It helps to turn off the O/D when not on the highway, too.

 

I get around 17 on the highway, and I'm driving a 2 door (I do have a PSC Brawler Lite/Warn 9.5cti-s winch) with 4:10s and an auto. I think a lot of that is the speed limit here is 70-80mph, and I'm always turning 2500+ rpms on the highway. I actually don't expect to lose much mpg when I swap to larger tires, even with the heavier rotating mass, just because my rpms are going to drop. I have ~3500 miles on my '12. My point being, expecting 20+ mpg is far-fetched, you might be able to pull it off drafting behind a semi on completely flat ground, or cruising far below the speed limit in most states. 55mph seems to be about the best I can do for mpg, I pick up an extra mile or two per gallon. A 10mph wind completely negates, that, though - and that's probably worse on the JKUs.

 

Could be worse, I average anywhere from 13.7 - 14.2 for normal driving... On the highway (2 hour + trips) I sometimes see 15.3 - 15.6.... 2010 6 SPD....

 

Mileage is for prius'

 

I don't think I am breaking any rules by posting this...

This is the government mph test description of how those window stickers get their numbers.


http://www.fueleconomy.gov/feg/fe_test_schedules.shtml

 

in my 12 auto at 45 I am either not in OD or I am lagging in OD, either way eco mode is off. At 55 I am in the sweet spot of about 1900 rpm in OD, the mpg goes up. Why would I turn OD off on the interstate? In my 2010 on 35s the jeep could not stay in OD and was constatnyl shifting down (agree, turn it off), result was about 13mpg at 78 mph. In my 12 on 35s at 78 mph i never leave OD, result 17mpg.