I'll add my $.02 to this thread. Just finished towing a 6x12 uhaul, loaded weight around 3000 pounds, some 2200 km from Winnipeg to Toronto via the US route. 2011 cx9 AWD, factory towing package, mazda hitch.
Observations:
Gas mileage; yeah, what you would expect. 10 liters/100 km out on...