Did 5600 miles towing with my Excursion this summer. 2wd stock height pulling a 5k pound hybrid. Had just about every terrain you can imagine averaging from 8.25 to 11 with over all trip mileage at 9.27 at 65mph. It had plenty of power to pull hills heading up to South Dakota and ran through the Texas heat without getting above 200 on my trans. I do wish I had done the Y pipe and tuner before but we all learn the hard way.
In retrospect, did 6 hours of highway driving with 4 adults and two kids for Thanksgiving at 68-69 mph and got 16.5 average filling up at the start and finish at the same pump at roughly the same ambient temp.