[cowmeat]

I ran a full tank of ethanol free gas in the Black Widow back in the day, and it had absolutely no affect on mpg, I just ended up paying about 8 dollars more for the fill-up.

Here's my Fuelly log of the tank back in 2012:

19 1/22/13 402.00 9.00 44.67 3.359 75%
18 1/8/13 400.00 9.00 44.44 3 .329 75%
17 12/23/12 398.00 9.00 44.22 3.179 75%
16 12/7/12 395.00 8.86 44.59 3.899 75%
Tried "no ethanol" gas to see if it would make a difference. Found out it only costs more, didn't make any difference in gas mileage.
15 11/23/12 417.00 9.39 44.41 3.259 75%
oil change with synthetic & premium filter = 40.00
14 11/12/12 430.00 9.62 44.69 3.299 75%

Doing the math, it would need to give you over 20% better mileage to be cost effective, unless it has other hidden benefits, like longer engine life, or suddenly turning your crappy econobox into a chick magnet . . . .