650 hp from a 3.5L

[Don Leslie]

I surprised it took so long to identify the fact that Ford does not own the name GT40.

Here are two views of what happened.

https://www.hemmings.com/blog/2015/06/18/why-has-ford-abandoned-the-gt40-name/

 

[rjdelp7]

My 2011 Mustang says 91 or higher. Use of lower octane will reduce performance. My 3rd auto is 2001 Lincoln with the Intec DOHC 32V V8. It to requires "premium", but will run on 87(like crap). Ford just re-worded it to fit the EcoBoost image and avoid criticism, of the added fuel expense. They run on 87, but with reduced power. The ECM will run slightly rich, to avoid detonation. It also pulls timing. Both cost power and fuel mileage.