Here's FUEL INFORMATION for Q50 from Infiniti
Use unleaded premium gasoline with an octane rating of at least 91 AKI (Anti-Knock
Index) number (Research octane number 96).
If premium gasoline is not available, unleaded regular gasoline with an octane
rating of 87 AKI number (Research octane number 91) may be temporarily used, but
only under the following precautions:
. Have the fuel tank filled only partially with unleaded regular gasoline, and fill
up with unleaded premium gasoline as soon as possible.
. Avoid full throttle driving and abrupt acceleration.
Use unleaded premium gasoline for maximum vehicle performance.