Hello JV,
Thought I'd answer your questions in a PM since posting to the forum was giving me trouble.
You're correct, having an automatic really hurts your hypermiling ability. I'd at least consider trading your car for a manual Forester if you could. Beyond that, what year is your forester? I'd suggest your first mod be a Scangauge if your car is newer than 1995. It gives you instant feedback on mpg/TPS voltage/etc etc. I'd also look into getting a block heater installed if you often take short trips. . .driving with a cold engine is murder on mpg's. Answers to your questions below:
As far as following semis, I drove a 2008 Pontiac G6 GT rental car last weekend with an instant mpg readout. Even following a semi at a legal following distance made a difference. With a scangauge you could be able to tell what the risk/benefit looked like and decide if it was worth it to you.
Depending on your year, you may be able to adjust the shift points by tweaking with the computer. Ideally, I think you'd just want manual control of shifting and converter lockout, which might not be all that hard.
"Fuel injector cut button" would be useful for engine out coasting (EOC) which probably isn't an option for you with an automatic.
"Open/Closed Loop LED"
This would somehow indicate if the engine was in closed loop (basing fuel off the O2 sensor) or open loop (basing fuel off lookup table). If you get control of the shifting, you want to keep the throttle below the closed/open crossover and keep the engine in closed loop as much as possible.
"SuperMID"
A device very similar to the scangauge, but works with OBD I cars like mine (pre 1996)
I believe all the bridgestone 381's are B381's. They only come in 185-70-14 though, so they might not work for you. Here's a link to take a look at:
https://greenseal.org/resources/repor...resistance.pdf
"Full moon hubcaps"
Ebay is a good source:
https://cgi.ebay.com/ebaymotors/ws/eB...050193225&rd=1
Or you can just google it.
"Wheel skirts"
My gut tells me the underbelly pan would do more, but I plan on doing both.
"Grill Block"
I haven't decided on this yet, I just may make a foam/fiberglass "grill" that has no opening.
"Flow turner mods"
I have a suspicion that I can lower drag by putting flow changing devices that keep the flow from separating from the car. Think something like a vertical wing on the windshield pillar that forces the air to transition from the windshield to going smoothly back by the side windows. I'm also hoping to play with a similar concept in hopes of reducing the wake behind the car.
As far as passing emissions. . .well, you didn't hear this from me, but if you did all my mods you could easily get it to pass emissions by reprogramming the ECM with an "emissions tune" for the test. <smirks>
I'm not sure how far I'm going to take this car actually though, because I'm pretty sure if I built an all-out Honda Civic I could get way over 100 mpg, while the best I could hope for with the Legacy is maybe 50. Time will tell I guess.
Hope that helps you somewhat!
Sam