I have a 1996 3.2 L 24V with 158K on the clock one head gasket and guide seals at 78K due to leak (still leaks).

I consistantly get 19- 20 in town and 24-25 on the highway at 80 MPH 89 Octane AC on. When the oil gets dirty at 6-8K miles (Syn of course) it drops 2 Mpg hwy and 3 city. I gets very consistant results with this car. Its amazing after that amount of mileage it still posts MFG spec gas mileage.
I did a 600 mile trip in july@ 65 MPH and got 28 MPG. the car felt limp at that speed though and felt like it wanted more air.