Another thing is how far do you drive each trip. If it never gets warmed up it will give worse mileage. Could be a combination of a lot of things. Make a list of the things that effect mileage and then do a yes/no and see how it fares. Correct all that are no and are reasonable to correct. See how it checks out then.
make sure it isn't lugging. You said automatic. If it is not down shifting properly it is going to be lugging the engine and that will burn more fuel. The 2.5 needs to be in the 1500+ range to get efficient torque.