It seems to me that many of you are exaggerating mileage. I have the 3.2 and am currently at 22.6 combined about equal highway/city. Also there is no 3.6 in the Cherokee.
There are many variables in mpg. I would imagine most of the reported readings are from the on board computer mpg screen.
The on board computer calculations are not that far off, as I have found on mine.
Even when you hand calculate there will be a difference over the fill amounts.
I do find a difference when I do not use the ACC (tech group) on the highway for even part of the trip.
* Your 22.6 combined is not bad combined. It depends if its 50/50, more, or less highway. My combined is all over the board. The only consistent readings I get are highway. In town can vary by as much +/- 2-3 mpg. That is 17-20 mpg.
* Trail Hawk is heavier and will get lower mpg.
* If you are using 4WD, like driving in Sport mode, even part of the cycle you will eat gas over the FWD mode that Auto mode defaults too.
* Type of gas you use, that is big City gas or regional EPA requirement on gas. has a big impact. For instance when I go to Chicago I try to only fill enough to get out of the urban area. That cuts my mpg back.
* Colder weather will hurt your mpg also. Mine has all ready been impacted.
I struggle jut to get close to 19.0 now.
* Individual driving habits have a huge impact on mpg. That's why I love ACC. It takes my driving acceleration/deceleration/constant speed and braking out of the equation. Net result is better mpg for me.
It also depends a lot if your Cherokee is fully broken in.
Mine did not even start using 8th till around 3,000 miles of so, maybe more.
That alone made a huge improvement in mpg. Even up to 5,000 miles it was still getting better.