You're gonna get crappy fuel mileage by having the back end squatted, you're always going uphill.
LOL. I realize that XJ and aerodynamics do not go well together but, I understand that there is a small amount of rake (higher in rear) designed into the XJ to improve airflow.
Also, due to rear cargo capacity and seating, would make sense to sit higher in the back when empty.
We referece it here as a "Cali Squat".
Comes from the offroad and Baja competition setup to land it in control from high speed jumping. Of course those racers took the lesson from observing stock Cherokees.
The Cherokee trends to it naturally as a function of weakened rear springs.
For Cherokees it is a characteristic to be corrected in normal spring maintenance.
My opinion, don't do it purposefully, leave it to the mud ricers.
Haha I had no idea it had a name! Ive seen it down here in southern California but it is mainly the mexicans who have their trucks overloaded or the "bro's" who think it is cool. I asked a kid from Lakeside (the eastern, redneck side of SoCal) why his truck was like that and we came to the conclusion that it resembles the desert trucks at high speed or taking off from a stop. Its 100% cosmetic for the "aggressive" looks.