On my first tank of the 2021 Carbon edition CX-9 I got 26 mpg (all freeway driving). But since then the gas mileage has dropped significantly. I get anywhere between 18-20 on freeways and 16 in city. I have shown to the dealership and they don't see any problem. Oil levels are correct, brakes are okay, tire pressure is good. I have 3000 miles on my car. I can't understand why it would drop like that. I have been driving the car with proper acceleration and breaking. Any guidance would be appreciated. Thanks!