The Flex fuel engines are more than a couple years old, but it certainly has to be an engine and fuel system designed to use E85 or significant damage.
I know Ford started offering it in 1980s but it was not common until more recently.
You are correct about Flex fuel engines being more than a couple of years old, but are ALL car engines currently or in the last few years, Flex fuel engines? When I bought my Saturn Vue in 2007, the Flex Fuel engine was an option to get, but not the standard engine offered.