That fuel gauge site is a GREAT SITE! Thanks for posting it!!!
According to GM the 2009 E85 engines have "improved computer technology and cylinder design," to be more efficient than previous flex fuel engines. When the flex technology was looked at in 2005, it was more a novelty than a necessity, and the engine tweaks were almost entirely with the engine management computer. How much better the 2009 flex engines are we will find out soon from consumer groups and vehicle testers.