Just to let you know, if you can get your hands on european diesel JK you are in for a treat. For a start your avg mpg will be 32 to the gallon (4.56ltr) (imp Gall, I think, are different to US Gall) I have seen 41mpg on mine but only once, 36mpg a few times. We have a caravan (trailer) that weighs 1.2 metric tonnes when towing this the economy falls to 24mpg but thats because I like to race Landrovers away from junctions, I shouldn't I know but it's fun to let them half wheel me then leave them standing with the caravan on the back.
At this point I should confess, standard output 175bhp at 2100rpm, I have a chip on mine and it puts out 215bhp at 1800rpm max rpm 4500 waste of time hanging on after 2600 the torque curve is so flat your just wasting fuel, mine is a six speed manual but fifth is a universal gear you can use it from 18mph to 85mph! this is the jeep we've all been waiting for, here in the UK JK owners are few and far between but the JK is catching on and it's won "Hardcore 4x4" for the second year in succession twice beating the very good but agricultural Landrover Defender.
The engine is an Italian made (was Mercedes in the early models) 2.8ltr 4 cyl common rail diesel with turbo and intercooler, noisy when cold, peachy when upto temp other than that everything else will be as your specs.