The engine !

My number one choice is this 11.6 cu in engine by airpowertechnologies;

http://www.airpowertechnologies.net/UAV_116cuin.html


It uses 1 oz at 65% ( 28,6 hp ) power that would enable MAX III twin with 170 mph cruise to go at very low consumption !

In fact it burns 3.360 kg per 274 kilometers and 1.23 kg per 100 km ! What is even better yet is that it would operate at 14,3 hp power on one engine alone and still cruise at 110 mph using 0,615 kg of fuel for 100 km !!!

This should beat any existing electrical flying machine by 10 %.

2-strokes are also versatile; http://books.google.com/books?id=t6w1i2Irp8UC&pg=PA101&lpg=PA101&dq=low+consumption+2-stroke+engines&source=bl&ots=EoNNeB5wKh&sig=LmQhYD3r8pDzmFT6OQ9e2LyT4qE&hl=fi&ei=Rj7ITJmAD8-dOoLfoPAI&sa=X&oi=book_result&ct=result&resnum=9&ved=0CEoQ6AEwCA#v=onepage&q=low%20consumption%202-stroke%20engines&f=false