I generally find it pretty easy to hit 10-30% above highway epa driving any car I'm not used to. Its really pretty simple, go the speed limit, pump up the tires, avoid brake use (a big one with as much as your vehicle weighs), and other simple things listed in the
100+ hypermling tips. 30% above highway EPA would put you at 28.6 mpg. So, high 20s are possible. However, there is no way you're gonna come close to that doing 85 mph. At 85 your vehicle requires over double the power to push it along vs going 65 mph. I'm not saying you need to go 65, but you can't expect to get amazing mileage at 85 mph.