Just experiment on diff fuels sir. Most EFI engines will actually run more efficiently on higher octane gas. May Altis runs 7km/l on Xtra unleaded and 10km/l on Blaze. So for my ride, in quantity mas mahal nga yung blaze pero in essence mas mura talaga ang blaze.
In your case, if you really want to try premium/super unleaded, I suggest trying one fuel for two full tanks then another for two full tanks again. Let your engine adjust. After every first full tank (each fuel) measure your mileage. Believe me you might find interesting results.
Last edited by Picard; March 16th, 2009 at 08:48 AM.