I'm surprised you can keep it on the road at 47 PSI! Would it piss you off if I were to tell you that I get 19 MPG with 32" BFG's at 34 PSI? That's at 70 MPH with the A/C on AND in mountainess areas. If I drop to 55 MPH I can hit 21 or 22 MPG.

Here's a thought for the older X owners. My X has always consitently gotten good mileage. part of it is that I've learned how to drive it for better mileage. For isntance, on steep hills more revs and less throttle works better than lower revs and more throttle. Try not to stop at traffic lights. Drive smoothly and time your drive so at worst all you have to do is slow down. Those of you that race to the next stop light and then slam on your brakes are killing your mileage. It takes a log of gas to get the Xterra moving again! People behind you will be pissed when you're driving along at 20 MPH, but they can go around...you'll get back by them anyway when the light turns green and you just kinda drive on by. Saves your brakes too (I get over 100K miles out of my front pads!).

Now, also check your maintenence items. Recently I noticed my mileage was going SOuth a bit...running about 16 - 17 MPG. I took the X in and had the spark plugs changed (they had 80k on them) and BOOM, back up to 19 MPG. Changing my cap and rotor and fuel filter on Friday.

Anyway, driving habits and maintenence are your best bets in changes to improve mileage.