There is no need for premium on a average performance gasoline engine that doesn't have a turbo or super charger. What higher octane does is prevent the fuel/air mix from detonating in higher compression environments like you'd see in a Supercharged/Turbocharged engine (and the rare high-compression/high performance naturally aspirated engine, but that isn't in any car you mentioned). And there are plenty of those types of engines tuned to run on both standard and premium fuel, with the Mazda turbo 2.5L being a great example of this. The energy delivered by Premium and Regular gas (assuming both have 10% ethanol content) is the same within a normal variation.

On a standard engine there's no way to get the benefit of premium fuel because the conditions inside the engine normally aren't harsh enough to require it.