The engine is tuned and designed to run on 87 octane! Octane is a NUMBER or rating that is used to express the resistance to uncontrolled pre-ignition, generally a slower combustion. If the engine is designed for a faster combustion (lower octane) then you will actually lose mpg by running a higher octane rating. (before you flame me this is for a layman's understanding of octane)

Ducit Amour Hybridae
Mark Smith
Master Certifited Technician
Tempus non reparabilis fugit
"It isn't pollution that's harming the environment. It's the impurities in our air and water that are doing it."

Best Tank 35.0 MPG