If your Subie is an automatic I can't offer any help. Nothing I tried could budge my numbers past 28mpg. AWD + an automushmatic is an unfreindly combo.
It's dying of old age, 200k miles, and salt on the roads. 3 holes rusted through, one of the computers is acting up, needs shocks, ujoints (or whatever) and another timing belt. It's just all arriving at once. I think if I could get it trough inspection I'd be tempted to keep it as a haul-big-things beater.
It has another 150k to go, it's not dead yet!
Rust is really what kills them. Grinding off rust filling holes with bondo, and covering everything in roofing tar seems to be the way to make them last longest.
The timing belt is surprisingly easy to do yourself. $45 at auto zone.
I've found it easiest to take out the radiator rather then trying to take out just the fans (as recommended)
FWIW, I'm getting mid 30's around town in a much older 5 spd Accord with little more than 40PSI tires, non cyclic P&G + (coasting in neutral, engine idling) and traffic light anticipation. Doing the EOC thing ought to get you close to 40, I'd think(?).