High mpg highway, low mpg city
 

My Nissan Pathfinder 2005, from day 1, has been getting VERY low mpg, under EPA in the city 12 mpg. (utah, so they have long roads going 30-45.) compared to 21 mpg on the highway going 90 MPH!, ABove EPA.
EPA:
15 city
17 highway
16 comb.

There is more driving being done in the city, so highway driving is not a priority. Any ideas for the cause?

Not in OD/tcc not engaged.

That would explain poor highway mileage, but he's getting good highway mileage so it can't be not in OD.

12 MPG city is normal for a 4x4 do you have the 4.0? Or the 3.5? Avoiding city driving helps :)

Generally the faster a driver goes the more likely an auto will be in OD w/ the tcc engaged. So... If highway is good, but ~30-45mph cruising is bad, I'm guessing the vehicle isn't in top gear and the tcc isn't engaged. I know mine won't lock up/downshift below 40mph when warm.

Fast acceleration, stop&go driving and/or heavy brake usage in town.

Those would be my guesses why you have the big Δ in mileage between city and highway. Lots of mass to accelerate and if you accelerate quick and don't ever get into a high enough gear or coast enough your in town mileage would suck.

Short trips and cold engines would cause that as well...

yea ive got the 4.0 L
I think the reason is that my dad drives it all the time and is always the first one off the line. He does coast alot..
still doesnt explain why its getting way above epa on highway :)
... if only i could reverse it.