I'm also very interested to start improving the fuel economy in my truck...
My first truck was a 2005 RAM 1500 w/ 5.7L Hemi and an automatic transmission w/o mods, and the fuel economy balanced out at ~14.6 L/100km (~16.11 miles/US gal.).
Liked it so much, I traded it in for my current 2011 RAM 1500 w/ 5.7L Hemi Sport. The fuel efficiency sucks!! (pun intended!) Same traffic routine, I baby the throttle to keep it at 16 L/100 km/h (14.7 miles/US gal.) I wasn't so good at feathering the throttle with my first Hemi!!
And here I thought that the new ECO mode would obviously give me increased fuel mileage!
Last summer on a pure highway trip from Calgary to Sicamous B.C., I was able to achieve 12.5 L/100km (18.81 miles/US Gal.) which is not bad, but not as good as some of the results I've seen here that makes me envious...(Grubrunner's photo from S&B CAI review
So, now I'm looking to start modding to improve things--but--isn't there an issue with aftermarket modifications voiding warranty coverage?