your spedo and aren't necasarily acurate to each other, there is usually a variance. The only good way to judge your odometer is to take a good high way trip that you will not be deviating for gas station etc. at a mile marker reset your trip meter and run it out as long as you can to get a good measure. 100 miles is best but I have ran a 500 mile test on a toyota. hit a hundred then take 100 and devide it by what your trip meter is showing. this will give you the multiplier to use
multiplier x recorded mpg (gas gallons devided by "miles driven" shown by odometer) = actual milage.
The same multiplier is usually good enough for use on the speedometer

 

100 miles = 5.62 gallons = 17.8mpg

 

here's what i've found out. the speedo is off with stock tires. by not too much. the only way i got the same reading from the odometer as i did from the mile markers and gps, is worn down 30" tires. they're about 29" tall.

 

218000 miles haven't changed any filters or anything, and I get right at 18mpg.

 

Dunno, been 160 miles on just a smidgen over 1/2 tank. Haven't had mine long enough to even use a tankful.

 

around 16 mpg here

 

1997 4.0 auto. 262000 miles 4.56 gears 35" tires right about 14 mpg

 

91 limited 4.0 HO depending on driving and 4x4 or not i get between 17 and 18.2
all stock. synth blend oil, new air filter

 

Mine is about 17 in the city and maybe 23 on the highway. I have a rough country 3.5in lift with 31x10.5x15r Hankook dynapro mt tires

 

14.5 per tank with combo driving

 

About 17 mpg, but I do mostly city driving .

 

5mpg... I think I may have a problem now....