First of all, FWD gets 1 mpg better than AWD, for 2020 anyway. For some posters I can't tell which they are talking about, but lets move on.
It is instructive to know how the EPA actually tests gas mileage:
This page provides the chassis dynamometer driving schedules and shift schedules used by EPA for vehicle emissions and fuel economy testing.
www.epa.gov
Click on the chart for the highway mileage test. It runs 12.6 minutes, 10.3 miles, with an average speed of 48.3 mph without exceeding 60 mphs. However it begins from a stop and at the end drops from 60 to 0 over about 40 seconds implying braking. The various zigs and zags along the way imply some braking and acceleration.
This is more typical of the rural two-lane driving in light traffic I frequently do--the 30 mph drop through a village, occasional light braking then reacceleration when a vehicle in front is turning. Lo and behold, I get right around the EPA rated 30 mpgs for those drives, sometimes a little better depending on circumstances.
So, if you enter an off rush hour urban expressway without hills with a 50 or 55 mph speed limit, reset the mpg display, and then are able to hold at the speed limit with no braking, cruise or otherwise, I'm sure it is possible to see significant improvement over the rated 30 mpgs for AWD or 31 mpgs for FWD. Thinking back now to when I lived in a very rural area (the county had no stops lights) there were stretches of straight, flat two lane road with no stops for 10 miles and a 55 mph limit, so there is that possibility.
But that's cheating. In the real world you start from a stop somewhere, drive some ways on surface roads, and then giddy up. The optimal real world conditions would be gassing up at a tollway service center, accelerate to highway speed over something less than a mile, and then cruise for some hundreds of miles before exiting right into another service center to refill.
I'm with
@IamVAguy. My more typical expressway scenario is 55-65 speed limits doing 62-72 mph yielding 32-33 when the traffic is free flowing. That's when tanking up, entering the expressway, and driving 200 miles before stopping. That would be consistent with the EPA 30 rating--little or no braking and reacceleration that we see in the EPA cycle more than compensates for the higher speed.
But here is the question: pre-2018 versions without CD would also see significant improvement over the EPA rating under the more favorable or optimal conditions described above in comparison to the EPA cycle. So what does it really buy us?