G'day Max, welcome.
You may have already read the 100 hypermiling Tips at the top of the page, but they're worth a re-read. You'll probably get more gain from driving technique changes than anything else.
You say you're not keen on aero mods ... no problems. If most of your driving is in town at 50 kph, they won't help much anyway.
The two most obvious "mods" to start with are:
Increasing tyre inflation somewhere between Ford's recommended setting and the max value on the tyre side wall.
Get a good tune-up and keep the wagon in good running order. Running rich or mechanical drag can make a difference at any speed.
Is the Falcon auto or manual? (please say manual
)
Again, welcome.
Pete.