I always got dam near 20 mpg auto ,stick, 4x ,2x, the milage difference is about . 5 mpg 19ish 4x4 auto 19. 5ish 4x4 stick 20 to 21ish 2x4 auto this is just average mixed driving and all trucks had 3:54 rears . winter fuel cuts it back a bit and higher highway speeds . I heard told 25 mpg on a 2x4 auto and 27 on a 2x4 stick I guess it's possible but this must be at grandma speeds i don't have the patience to find out . mike