Off road

We live in Qatar and bought a second-hand 2013 Nissan Patrol V8 with 94,000 km on the odometer. While we were driving the car it broke down. I was driving at 120 km/h and trying to accelerate, the tachometer went up, but the car didn’t move forward anymore. I stopped and tried doing the same again; it moved a little bit but tachometer went up and then the car didn't start anymore. So we took the car to the garage here in Qatar and they told us that there was an automatic transmission failure, and the cost would be around $11,000, including labour. Can you tell me if this is a correct price for this type of car?

What is the difference between 4WD and AWD? Previously, it used to be pretty easy to distinguish the two but looking at the cars available, it is hard to tell ie. Amarok doesn't have a low-range, some utes have diff-lockers, my Forester has one of the better AWD systems with an X-Mode to further aid traction. The reason I ask is that I wish to begin to take my Forester off-road (sensibly of course). If I see a track that says '4WD only', can I assume my car would be able to handle this track in good weather, with a sensible driver?