They were the basically the same from 2005 onwards. I think they added more airbags in 2009. Maybe mileage is tweaked a bit better later too. I think later ones had a better rear diff too, but that's mostly for off roading.
A co-worker of mine had a 2012 that he had for 3yrs and ~70K miles total on the ticker. No issues at all but averaging ~16mpg tank/tank. You could drive a V8 Ford Expedition or similar and get similar MPGs.
The Xterra is often an overlooked, affordable 4x4. Does anyone know what year model is the most reliable?
I have a 2006. Typically the latest year of a model run is the most reliable, I would go with the 2015....that's when the most bugs have been worked out. I've owned mine since new and have 234,000 on the clock. Original engine and tranny and both are working well. I have a minimum 92 mile commute every day in mixed driving conditions and I average about 20 mpg throughout the year.
Any year after mid 2010 production since they fixed the radiator cross contamination issue and Borg Warner fixed the timing chain so they don't wear out the timing chain guides at a high rate requiring an expensive fix.
Last few model years were quite reliable the V6 is not that fuel efficient although a real strong and durable motor. Can be tough on motor oil has a tendency to shear oil down fast. Run a 10w30 or 40 weight in the summer and a good 5w30 in winter. Oil filter can be a pain in the --- to change.
Go on www.truedelta.com and check out your desired models. They have real world reliability information on nearly all makes and models. There is some input there from owners and some common problems. Including enlightening information on just how expensive the repairs actually are.
For example a Toyota may need a transmission repair, but it's only a solenoid, mounted externally. $400. A VW may need a transmission repair and the Mechatronic unit needs to be replaced, $3400.
We had a 2005 with the 4.0l V6. I did the bypass to take the ATF from running through the radiator so it was never an issue for me like it was for others. That VQ40DE engine was rock solid for 96k miles. Engine used no oil between OCIs. When we sold it, it had just started to whine a little due to the timing chain guide issue. People who bought it didn't care, they just had to have it. It had been well maintained and it showed.