the MPG is what it is... but really depends on driving habits and what mods you do... big tires, heavy bumpers, roof top stuff... wont help any... but make for a fun ride off road.
The inverter came with different packages over different model years. If it is not included don't despair, the wires are all there and you need need to add an inverter.
as for roof top tents it all depends on the model and mounting... Corey has his tree house mounted on top of the factory roof rack.
