85% ethanol vs regular unleaded?

as i filled up my car today, i noticed a separate pump with 85% ethanol on it. how does one make the choice to use the 85% ethanol fuel? can anyone use it (does it matter what kind of car you drive)? does it mix with regular gas?

there seemed to be no price difference between the regular and 85%.

i have only seen it at this mobil station (which i try very hard to avoid due to the 21 cents more per gallon prices…)