Ecos are great engines, no question at this stage. They deliver great mileage when NOT towing but when you hook up, mileage goes down to where most of the rest of us are. They never claimed superior mileage when towing.
If you insist on towing at high speeds then go ahead and do that. Your mileage will suffer, that is established fact. Couple that with towing a long and heavy trailer with a flat surface pushing the wind will not help you out much. So about the only thing you can do to help is to slow down. Argue if you want but that is the fact you are facing.
