hi....our 4.8 is a 2010.....and mileage combined would be around 21 or so combined as we
do 60-70 % city driving. I would think the gearing in our 2010 would be different than that
of an 06', thus resulting in a little better mileage....no modifications yet....want to do Cold Air
Intake and am thinking of trying a Throttle Body Spacer(unsure) just to see more horses when
I want them and to see if you can really get 5-10% better mileage with Cold Air Intake..
take care........Brian...have a swell afternoon