First commute yesterday... and the trip average was 30.4 MPG, even with rain on the morning route. Lately, with the cold weather and my new calibrated ScanGauge giving more accurate results, I've been averaging about 25-26 combined. So it looks like I've picked up about 4-5 MPG, or 20% FE increase! Not bad for a couple sheets of foam and some sanding.
Now I'm hoping that summer will get here soon, and with a belly pan I might just see 35 MPG!