cgrams I agree with your findings on the 3.9 verses the 3.5. I also have a 2011 with 3.5 and now remeber why I bought the 3.9 in the 2008. The 3.9 gets as good or better mileage than the 3.5 and has the power to motor up and down the hills without shifting or dogging down. I wanted a 3.9 in the 2011 but did not want to buy a LTZ to get it due to the tire life and replacement tire prices on the LTZ. That is an issue for me with the amount of miles I run.