and don't forget - due to its lower costs - you don't need to fill all 78 seats to make money. Don't know what the break even is, but it depends on yields etc.
As for relative fuel economy with other transport, not sure how meaningful this measure is, how about looking at cost of providing high speed rail line compared to new runways? ERA have a lot to say on this subject:
http://www.eraa.org/publications.html#discrimination