mine is the same way. its 5 mph off (speedo reads less than actual), however when youre on the highway be careful, your speedo shows you going 10mph slower than actual. your odo i think is off 1 mile for every 5 miles driven.
My speedo is 2 mph faster than gps speed. I'm screwed... (I also need to get the tuner out and fix that)
na i got mine figured out. in a 55 i go 50. on the interstate i go 60 which is really 66. good enough for me
would you guys believe me if i told you that my 15 year old 4x4 with the 5.4. runnin 6000 mile oil and a dirty air filter got 18.5 miles per gallon today!!!