With the cap removed, the gas tank’s opening is now exposed and you are ready to refuel. Be sure to use unleaded premium fuel with an octane rating of at least 91 AKI (93 AKI is recommended for peak performance) and keep in mind that the 2018 Infiniti Q50 has a fuel tank capacity of exactly 20 gallons—unless you have a hybrid engine, in which case fuel tank capacity is only 17.8 gallons.
Once you have finished refueling, replace the fuel filler cap and turn it clockwise until you hear an audible “click”—this signifies it is locked securely in place. Firmly shut the fuel filler door to latch it.
MORE: What do the gas octane ratings really mean?