What say you all? I've got one person insisting on premium (mid-range) and another insisting you're not supposed to use premium. This would be for a US model, US gasoline, if that's worth a difference.
It should say in your users manual what the minimum grade gas you should use. I'd use that as your baseline. However, there are reports that indicate higher octane fuels aren't as effective at higher altitudes, so I'd just go by what you feel performs best in the car.