4.7 with factory towing package. 11.5 MPG at best and 11.0 worst. I moved at 70 MPH at 2100 RPM.
I should also add that I got 11.5 with the A.C. on.
I will also add that get brakes for the TJ trailer, and get as light and small as possible. I was towing on FLAT highway. I'm using a 18ft trailer and am saving for a 16" lighter trailer hopefully aluminum. It did struggle going up sometimes, but I have been nothing but impressed with the 4.7 and my commaddy as a whole.
If you are looking to buy new check out the website of the dealership if you can and scan the inventory. I wanted adjustable pedals and a towing package, she wanted blue.
Ours has No chrome, No Hemi, No NAV/DVD. Everything else I got...for thousands less.