For all of you octane hounds, this is what Mitsubishi says about compression ratio vs octane recommendations on their cars:
Mitsubishi Motors - Specifications
My local Mitsubushi service manager says using above mid grade with a 10:1 compression ration is a waste of money. I've tracked every tank for 19900 miles
and found mid grade delivers the same mileage and performance. If these cars were turbocharged premium would make sense. Every gas car Mercedes sells in the states says to use premium even though it's not really needed.
There is nothing special about the engines in these cars.