So at this point, I've come to the conclusion that the "best mods" for FE may be completely backwards of what we'd all expect.
153.5 mi. @ 5.144 US gal = 29.84 MPG
As it stands...this has been accomplished by the following:
1) two lower air deflectors from an 9C1 Caprice Interceptor.
2) My rear mud of flaps are still un-installed from when I was using skirts
3) Light Bar and fog lights
4) Aluminum Pulley @ stock diamter
5) Ebay Racing header.
6) Frankenstein exhaust with 2-1/4" glass back and 2-1/4" Thrush Welded Muffler
7) DIY cold air intake
8) Anti-fouler space Mod for rear O2 (catalytic effciency sensor, read P0420 code on subaru outback/impreza/2.5L/EJ25 motor)
9) Full interior in trunk include spare tire and jack
10) no other aero mods (removed grill blocks, removed front air deflectors, removed rear skirts)
11) use of an Ultragauge (UG)
This basically goes against all eco-modder logic...but there may be a reason...
1) The ~4.3 lbs from the pulley weight reduction is obvious, less rotational mass = less energy wasted, and with the AWD system there is more than enough inertia in the drive train to keep up a good coast.
2) The header has a wider diameter port, shifting more power to top end, the stock ecu is capable of handling the header. Keep less power on the bottom end may have reduced fuel comsumption. The header has increased acceleration while in the 2.5-4K range. Reducing the duration of high fuel consumption during acceleration. The Subaru's fuel peak in 4th gear on the highway occurs around 2750 @ ~62mph, was was pre-header information, but with the intake and the Frankenstein exhaust.
3) As per the skirts and air deflectors, there may be a difference for high speed highway driving, but majority of the subaru economy is all lost in acceleration due to AWD and heavy car. Most of my commute is all 45-55 MPG and drag occurs as ~V^2. The density/viscosity of air has little effect at these speeds.
4) Neglecting my previous statement...the push bar is now giving the hood/frontal area a "breaking edge", one of which is lower than the actual hood by several inches. Similar to how divers can break water surface tension with elbows, knees, chins, etc, this forward edge may be causing a mild, but plausibly effective difference near 55 mph.
5) The UG's throttle position readout is an absolute god sent gift. I can now keep the throttle ~2% without having the auto trans kick down and out of gear. But at the same time maintain speeds while avoiding excessive fuel consumption at a 10% throttle.
Feel free to discuss. But as of right now, I'm fairly happy with this result.
