Used 2021 Genesis G80 Advanced 2.5T Prestige

Options: Prestige Package, Advanced Package. The owners manual leaves a lot to be desired. It is hard to find explanations of the numerous features. Ride is smooth as silk, with windows closed a boom box next to my car is silent, acceleration is remarkable for a car as heavy as this. Gas mileage is terrible though. Around town, I get 16 mpg with a light foot. On the road, I get around 19 mpg. Wondering if there is something wrong with my fuel delivery system. Have not asked Genesis for valet pickup and drop-off of my car for service but based on comments in the G80 blog, dealers are reluctant to deliver on the promised service, not to mention they say loaner cars are not available.