The only problem is that non flex-fuel vehicles don't have the sensors necessary to detect ethanol content. They also don't have the control software to manage the air fuel mixture properly.
What Is Flex Fuel >> Fuel Gauge Erratic - 2000 Flex Fuel 3.0 - Taurus Car Club of America : Ford Taurus Forum

What Is Flex Fuel >> Fuel Gauge Erratic - 2000 Flex Fuel 3.0 - Taurus Car Club of America : Ford Taurus Forum

Bioethanol – When extremely high quantities of flex fuel locator are combined with suprisingly low quanities of petrol, it results in a fuel called bioethanol E85. This is a extremely powerful nevertheless environmentally friendly fuel.
What Is Flex Fuel >> 2011 Chevrolet Impala LT 3.5L Flex-Fuel Engine - YouTube

What Is Flex Fuel >> 2011 Chevrolet Impala LT 3.5L Flex-Fuel Engine - YouTube