Spartan65USMC

I've been utilizing the Fuelly application which compiles data for mileage average fuel cost, total fuel cost, total gallons and Avg MPG, Best MPG.
Since I put the 285/70r-17 Nitto Trail Grappler MT on my 2014 AUTO JKU I notice my mileage has gone down. With the stock 3.73 gears I was thinking 4.56 would give me some pep and room to grow into.

Scvette01

So did a little experiment today... Drove out to the local 4wd shop to get a quote... 45 miles one way, all highway

Drove 65-70mph and used OD... MPG went from 14.7-14.9 by time out got there... Lots of long up and down stretches on the highway. Lugged uphills and ECO off a lot....

Drove home same exact way, used 4th gear only, rpms up around 26-2700, right at the edge of the "green"... approximately where 4.56 would be using OD (according to the calculators)

Mpg... climbed up from 14.9 to 15.8. Was able to hold speed up the hills, ECO stayed on even on 90% of those inclines, and few times accelerated up to 75mph.

So engine load is more detrimental to fuel economy then the extra 300-500 more rpms

I think...lol

ronjenx

You have to consider head wind/tail wind on you bi-directional trip. And, also consider which way would have been an altitude gain and loss.

tarpon4me

I'm running 4.56 Yukons, 35x12.50 Cooper ST Maxx tires, manual transmission. I track my mileage the old fasion way by dividing my miles by the gallons I put in. I average 16.5 to 17 mpg consistently with a mix of highway and in town driving. I generally keep the speed at 65 mph which runs around 2350 rpms. My jeep is a 2 door and weighs 4500 pounds.

With that said, you can expect to never get good fuel mileage out of your jeep. It is, after all, a jeep not a Nissan Altima. If you consider the minor difference in 17 mpg vs 15 mpg, you'd barely feel it in the pocket.

Drop some 4.56 gears in and enjoy your jeeps new drivability. Don't forget to program it!

Dexter Morgan

Ive an auto '08 with 5.13s and 35/12.5/17 and would never go back. Drives like a dream off road and the highway.

Sent from my Galaxy R2 UNIT

Scvette01

Going to in the next couple of weeks... Going to install with what friend of mine.

Really looking forward to how it feels afterwards... Especially leaving a stop and acceleration