It's not about the octane people, it's about a turbocharged car, with a fuel set up and tune for E85. It been done a thousand times, not by any Ford Focus people, but it's been done.
2015 F150 4x4 3.5 Ecoboost
2002 Camaro SS, new turbo install in progress...
2005 Neon SRT-4, Big wheel stage 3, E85