were you driving in the same exact conditions?
do you know which way the air was blowing?
when you off road you will not get great MPG. so if half was highway and half was off road will effect the MPG.
from the factory the best jeep could do was 14/19 and that at ideal driving conditions and most dont see that. but your driving a jeep if you want MPG look at a small car that is not a 2 tone brink on wheels
check to see if you have any codes that is effecting your "system" with a ODBII, most auto stores will do it for free.
can look into doing a full tune up and basic things to keep it running in top shape
You forgot to ask if he was heading up hill or down
On topic, i agree. Constantly resetting your evic will not get you an average. It will just show how bad you drove on that tank of gas. Also,
did you use cruise on the way down, and not on the way back?,
where you heavier due to mud on the way back?
Where your tires properly aired?
Did you bend an axle?
bend a CV?
where your brakes grinding?
Is your alignment off now?
did you make sure your turn signal fluid was full? (had to say it)
Get your codes checked, give her a tune up like straty said, and pray for that extra 1mpg. my 99 4.7 gets an average of 16.5, little better on the highway due to using cruise but not much. and i have only 83k on it, and im running 245/70/r16's and stock suspension.
Or buy a sissy foreign hybrid and quit whining about driving a real vehicle that sucks gas like a fat kid on cake after fat camp. Cause gas guzzeling V8's are the american way. Screw some sissy gas sipping pansy foreign hybrid. Give me a good ole gas eating, screaming V8 like my grampa had when my pops was but a twinkle in his headlight and a tickle in his crankshaft.