Towing capability of Subaru Outback XT

Towing capacity also includes you, your passengers and your stuff. You will probably be overloaded.

According to the manual, the 'additional car load' includes passengers, your luggage and the tongue weight of the trailer. This total weight should not exceed 900 pounds. My wife and my combined weight is under 300 pounds and the tongue weight of this trailer is ~ 250 pounds. We would have up to 350 pounds of 'stuff' in the car. They then go on to state the weight of the towed vehicle, attached to the car ( minus tongue weight) and weighed attached but separately from the vehicle should not exceed 3500 pounds. The manual also says I should get 23 mpg in the city and 30 on the highway with the turbo 2.4, I have never achieved either of these, even under perfect circumstances. Hence my question, what is the actually performance of this vehicle with tow of ~ 3000 pounds?

The performance with 3,000+ pounds will be glacial in the hills. If you want performance while towing that much get a F150. With this much weight you also need trailer brakes. If you plan on doing a lot of towing get a better vehicle.