Why is the price difference so much higher here?Probably. Depends on if FCA looks for higher output or higher efficiency, but current design on the platform would essentially require premium fuel, although at altitude you might be able to get away with mid-grade, but even then.. probably not.
A few of the small turbos out there like the VW 2.0L B-cycle in the Tiguan can use 87 Octane, but most require premium 91.
The problem being that often the efficiency gains are lost by the cost of fuel. As you know, here in AB it's a 15-25c premium... for Premium (sometimes 20c or more for midgrade), which can amount to 20-30% higher fuel costs kinda killing the benefits.
One thing that was great about driving in the maritimes this summer was premium being only ~ 5c more than regular (though all much higher than our reg) so went for the altitude and octane power boost while out there.