I have a 2014 Dodge Dart I-4 multi air turbo automatic with 110,000 miles. The mileage has gone down the tube here in Oregon. The vehicle in its hay day would get 40 to 45 on the highway and 35 to 37 in the city now everything is between 28 to 31 mpg. New plugs at @ 95,000 and coils, new air filter recently. All oil and filter changes are current. I have heard it could be the Oxygen sensors? They have never been changed. But according to the manual they are due.