Scott Pruett is driving a 3.5 ecoboost in the United Sportscar Championship. Won in Sebring and Long Beach. I don't think Ford is doing this to sell more Taurus SHOs. I think they are developing this engine for future application in the Mustang. Much like they did with the Boss 302R. Just a guess.
I think the 3.5 EB will find it's way into the Mustang at some point. Ford has to be doing this for a reason beyond this one race team in one series:
http://fordauthority.com/2013/10/watch-fords-3-5l-ecoboost-v6-engine-undergo-endurance-testing-in-a-specialized-dynamometer-lab-video/
I'm guessing that in a year or two, they'll position the 3.5 eco boost between the 2.3 liter 4 and the V8. If the EB 2.3 is +/- 305 HP and the V8 is 430+ HP then the EB 3.5 would slot in there nicely. It currently makes 365 HP in the Taurus. They just developed a racing version of the 3.5 for...