99 Coupe with 4/mt. Under 3000 lbs and a stick gets me pretty good mileage, even with >190,000 miles on the car.
I have checked my odometer several times against two different GPS units, so I know that the mileage is accurate.
I check mileage at every fill. That's a good way to monitor your car for problems.
I've gotten 31 mpg from my best tank. I regularly get 30, and my worst tank was 27 mpg. I have a combination of town and highway driving from most tanks. I get about 30 mpg in town by short shifting and skipping gears. I rarely turn the engine over 1700 rpm before shifting, plus I always shift up if going downhill or cruising on the flat if that lets me drop the rpms without lugging.
The f23 has a very broad torque curve, so it's a good engine for my high mileage driving technique.
On the highway I cruise between 68 and 78 mph. I don't know why the car gets the mileage it does; it seems better than I would expect.
It has been in the family since new, and well maintained. When I got it two years ago I did plugs, cap, rotor, Air filter & PCV valve. It still has the original clutch. A lot of the mileage in the car is highway driving, and it hasn't been abused. I run it hard through the gears once in a while, but it's so slow that it really doesn't make much sense.
One factor might be the tires; it's got a very ordinary all season radial. These are a ~70,000 mile tire, so they have minimal rolling resistance. They also suck when the road is wet, and are marginal on dry pavement. I hate them, but can't afford to replace them yet. I'm willing to give up some mileage to get better traction, especially in the wet (and Florida can be really wet at times).