Why do you care about running it at 2200 rpm? 6th gear at highway speeds is like 2300rpm.
If your worried about gas mileage then you will see zero noticeable difference between 1800 and 2200 rpm if your maintaining speed. In fact depending on the type of road, hilly vs flat, you might get less gas mileage trying to keep the RPM's low because your making the engine work harder to maintain speed.
The amount of load on the engine is what makes the big difference in gas mileage, not 400 rpm. Your barely above twice the idle speed at that point.
2012 Mustang GT, Brembo Pkg, Yellow Blaze Metallic