Flex fuel vehicles have a few items that make them suitable for ethanol based fuels: adjusted range injector feedback & monitoring, alcohol resistant gasketing and lines, and electrically isolated fuel systems.
Ethanol is conductive where regular gasoline and diesel aren't. While ethanol is a viable alternative, performance does suffer considering the BTU output so your mileage is greatly decreased. The yield is usually 75% of gasoline so while ethanol is usually cheaper, the saving is offset.
Brazil is a large producer of ethanol however they are also a big oil producer. There are several massive offshore platform projects under construction for Petrobras that will increase their output by 10% each as they come online.
I was involved with two of these platforms, so knowing their capacity I decided to buy a Hummer
