I think it's only logical Ford does it, mostly due to the new CARB and fleet fuel regulations. Quick simple maths show since the EcoBoost 4 would raise the fleet MPG of the Mustang line ford wouldn't have to "Tax" those in the GT and higher trims hence keep price down. Also if its out at or near launch think of how much it would bloody up Camaro and Challenger sales, which neither will probably add a 4 anytime soon plus neither really have a potent 4 cylinder engine that compares to that from the Focus ST. And now aside from giving the other 2 from Detroit a proper thrashing, it has a powerplant to run with the Europeans, plus it fits the entire Global platform idea 1 car same engine world wide. And finally with over 300 HP and drastically reduced weight, and a IRS, and lets figure with prcing where the base V6 would go to around 23,000 and a ecoboost option is about a $3000 premium, that would make the "SVO" around $26,000 which then you can fo doughnuts around a Subayota BFR-SZ while giving the international sign for Winner!