Chase, I don't think people should be using the 50 mile light as an indicator. I think it really should remain miles traveled divided by gallons used to get to full.
I say this because I believe it even says in the owner's manual that the "miles left" is a sliding average based on the last 400 miles driven. So the 50 miles until empty indicator is not really accurate.
That said, with my stock 15 inch wheels, if I'm on the highway all day I can get upwards of 43 mpg. Now I just have to prove it!
2011 SE Manual - black exterior/interior
Eagle Eyes halo projectors using 55w 5000K DDMtuning HIDs
LED Conversion (license plate, map/dome lights), and LED Taillights
Autobots decal over Ford emblems
Flat black TFB Designs hood stripes