The fuel that is being made these days is garbage! And I can assure you that the 1.5L turbo engine has a high cylinder pressure due to the direct injection and turbo charger being used to make that small of an engine create the kind of horsepower it has. Now if you shop in performance parts magazines they sell cylinder heads that are called quick burn heads! These cylinder heads are designed to burn regular gasoline without causing detonation problems and are low compression. So, How can you get away with burning regular gasoline in a engine such as the dream works direct injection and turbo charged engine with a higher cylinder pressure without causing detonation especially on hot days where the underhood temperatures are well over 200degrees? You can't do that my friend! Regular gasoline will catch fire under compression and high temperatures without the sparkplug even catching the charge on fire! The piston would be about three quarters of the way up its stroke when the fuel will catch fire on its own without the sparkplug doing it in time as it is designed to do! The timing is very critical when the sparkplug is supposed to light the air/Fuel mixture pushing the piston down on its power stroke making power at the exact time needed! And I know of no variable Valve timing components that can correct that! So I would say it is not recommended that you use premium fuel in hondas 1.5Liter direct injection and turbo charged engine, I would say with the cylinder pressure that engine is creating that it is a must that you run premium fuel or your begging for trouble with detonation problems in summer heat driving conditions! I heard a guy say that in a race engine, If you experience detonation it is the equivalent of a sledgehammer hitting the top of the piston with four thousand pounds of pressure! And failure is right around the corner if not immediately corrected! I have heard that the sound your hearing when an engine is detonating is the piston skirts slapping the cylinder walls back and forth and sooner rather than later your gonna crack the piston skirt off allowing the piston to turn sideways in the cylinder and immediately destroying your engine!