jskirwin 
2006 Nissan Xterra SUV SE 4dr SUV (4.0L 6cyl 5A)
A Rolling Money Pit
 There's a very good reason why this truck has been rated as one of the worst used cars to buy. We bought our 2006 new. Mechanically things were fine for about 40k miles, and after that the truck simply fell apart even with constant maintenance.After warranty expired I replaced: Windshield. Both window lift assemblies and controls. The bearings and control arms on all 4 wheels. The rear differential. Rear lift arms. Alternator. Spark plugs and wires. Catalytic converters. But worst of all was the radiator/transmission cooler failure. That allowed the coolant to mix with the tranny fluid killing the transmission. It is a known problem - so avoid this truck and the heartache it brings.Because of the ruined transmission I ended up selling this vehicle to a dealer for $900 with 170,000 miles on it, which is less than I paid for many of the repairs. Worse vehicle I've owned since the 1980s, and because of Nissan's refusal to help, I'll never buy a car from them again.2017 update: Avoiding Nissan is easy. There are plenty of better SUVs out there. Don't know whether the later gens fixed this problem but I would still make sure this problem has been fixed before buying a new/used one.2018 update: This was one of the last truck based utilities on the market before it was discontinued. It’s a shame Nissan screwed it up. It could have been so much more.