If you decide to go to the 6.4 hemi, figure on doubling your gasoline budget to feed that thing. Its a very capable engine, and has 9 ft lbs of torque more than the Ford 3.5 Eco (429 vs 420), and Car & Driver had it averaging 11 mpg. It was a little slower than the Eco in the 1/4 mile (16.1 seconds), but the Ram is pulling around about 1400 more pounds in weight empty. It'll sure have way more payload than the F150 Eco. Wish Ford would put an Eco option in their SuperDutys, maybe we'll get that when the aluminum body SuperDuty comes out in 2 years.