Hi, I drive subes, never the ej engine version.
A fuel injected loyale with simple mods 38mpg everywhere, hiway/city ...
A carbed sube is like a beetle, it could be doing anything. My own has gone from low twentys and 128 mph to high 40s and 50s sluggin on hills in the 70s.(all the same engine and carb, its kinda fun ...)
The injected discipline for the wrx is embarrassing...good luck for a goal of mid 20s mpg, and I am quite serious.