Not sure if its normal for my truck but i had a 2007 LMM amd had it tuned and I would get close to 23mpg in highway going 70, 17 mpg city and towing my fifth wheel i got 11mpg. Now i have an LML that's tuned and I get 9mpg towing same fifth wheel, 17mpg on highway and 15mpg city. Kind of dissapinted in the LML mileage. Both trucks had full exhaust and deleted emission. Lml has different tires too but not sure that would account for that much difference.