Well, they all turned out more HP with the premium and all but the Honda had better 1/4 mile times. That's something. Basically, turbos, especially 3.5 Ecoboost, run a little more efficiently. You can choose whether the price justifies it. Locally, it's a $.30 jump to 89 and at least an additional $.35-$.40 jump to premium. So a $2.70 gallon (current pricing) regular is $3.40 premium (26% more).
I have a premium tuned car and an Ecoboost, so I do buy premium. It has it's place in certain applications, which most of us already knew.