Fuel mileage

Bought car in Idaho got 35 mpg highway 29 city took to Florida 24 highway 17 city fuel mileage began dropping as soon as i crossed into Texas further south I went the worse it became how can I get fuel mpg back up to the 30’s Thanks Dan

It could be anything. It could be fuel formulation, new tires, difference in terrain, poor maintenance, or an engine problem in need of repair. Just the fact that you used different fuel pumps could account for some of the variation. The tires might have been overinflated when you bought the car, or they could be underinflated now. You don’t have a teenager or young adult who drives this car sometimes, do you?

I would start by eliminating factors and do an experiment. Find a gas station close to your house. With the tires cold, check the pressure and make sure it is what is listed on the plackard on the driver’s door frame or in the owner’s manual, not what is listed on the side of the tires. With the engine warm, fill up the tank, write down the numbers on the odometer, and take it for a drive on the highway for at least 50 miles round trip. Then go back to the same pump at the same station, fill it up, and calculate your miles per gallon and let us know what it is.

If you are not happy with the numbers you get, it is time to check the maintenance schedule. How long has it been since the air filter was changed? How long has it been since the spark plugs and spark plug wires were changed?