New member, first post. So, I have a new (to me) stock (for now) 2016 Tiguan and a convenient gas station nearby that has 87, 89, 91 and E85, all at the same pump (diesel too, but that is for my other VW). Compared to a full tank of 91, 12 gallons of 87 and 4 gallons of E85 yields 91.5 octane and is about $15 less per tank. The $15 aside, what are the +/- implications of taking advantage of the savings? Thanks in advance for your response/s. DN.