What is a "flex-fuel" car?

Question

What is a "flex-fuel" car?

Answer 1

That means it can run on gasoline or E85, or a mix of the two.

Not diesel or bio diesel - flex fuel cars are spark induced ignition not compression.  

Answer 2

PMack is correct, vehicle can run on any combination of gasoline or E85 ethanol...

the E85 is supposed to be better for the environment, but it drops your MPG

Answer 3

the other answers have it, though it should be noted that for the best economy and fewest emissions, you should try to burn as much out of your tank as possible before switching back and forth

ethanol has fewer btu's of energy than gasoline, so it burns more, but burns cleaner.

(i've never seen an e-85 pump anywhere, it'd have to be alot cheaper before i'd consider it... s***w the environment, lol)