* Older models (early 2000s and before): These tended to have lower gas mileage, often in the low 20s mpg (miles per gallon) combined (city and highway).
* Later models (late 2000s): These might see a slight improvement, possibly reaching the mid-20s mpg combined, depending on the engine and driving habits.
To get a more precise estimate, you should specify the model year and engine size of the Dodge Neon you're interested in. Then you can consult resources like the EPA's FuelEconomy.gov website or a car specifications guide.