A friend of mine owns one,first,the 3.0l turbo diesel is a mercedes benz engine,so about reliability,dont worry,its a totally different vehicule compared to my crd liberty,the transmission seems to be ok,but he s only at 40k miles,so we ll see,one thing that surprised me,it drinks!Lots of power/torque,smoother ride than the liberty,like more refiened.
It does feel heavy,but the security feeling in the winter is there,like nothing could stop it,but you know,a jeep is a jeep,good tires,good driver,and you go everywhere!
For sure if i get a deal in 1-2 years from now i ll get one,since i do lots of long distance drive,so for me it would be a better vehicule.
Average that i can tell you,16-17 mpg city(a bit heavy foot)and around 22-24 highway,so i guess that for 5000 lbs vehicule its not so bad,but like i say,if he could just stop pushing that pedal for the torque feel,i bet he could at least get 3-5 mpg more.
I really like that grand cherokee,and for sure i ll get one someday.
As for reliability,well theres no known problems for now,but hey,only time will tell i guess!
One only thing i dont like,is its a full time all wheel drive,plus you have a little chrome handle you pull to get it locked/low geared,so no way to let it on 2wd during the summer or highway driving,but the awd is elctronic,so i guess it is 2wd until it needs to go 4wd,but that,i cant confirm.I think jeep made a mistake doing this,i prefer to control my stuff myself,but they had to follow the other ones...