I just found out a common trip for me that I rerouted to improve my FE by 35% turns out to be 38% longer. I didn't think the difference was that much, but it turns out I'm burning a bit more on total gallons.
I'm going to double check my odometer reading. One way is pretty twisty and might not have been calculated fully on the map.
So I guess my graph will start creeping back down again, oh well. Less gas and money burned. Since my skills have been improving it might not go back that full 35% though either.