just to chime in here. when i had my 4.10's i saw a 8mpg drop in milage from stock 2.73's in my 98 on a trip to Ft meyers Fla From Pittsburgh.
30mpg down to 22mpg same trip same car.
the next year same trip with 3.73's and addition of an 11 psi procharger returned 26mph.
4.10's do get...