I wonder if these guys would have gotten even better than 110 miles a gallon without (I assume) ethanol in their mix.  After all, ethanol lowers the amount of heat stored in the fuel:

[Ethanol] contains only about two-thirds as much energy as gasoline. Thus, when it gets blended with regular gasoline, it lowers the heat content of the fuel. So, while a gallon of ethanol-blended gas may cost the same as regular gasoline, it won’t take you as far.  [Robert Bryce, Slate]

As I’ve blogged before, I’m glad to see more evidence of Prius fanaticism, even when it’s taken to rather ludicrous extremes (driving 1400 miles in circles is hard to justify as "efficient" ;-).