at have questionableFake motor sound doesn't work well yet.
A few folk here use devices like high pitched air (motion) powered noise-makers or a couple of other 'deterrent' style device,along with some surfacing and reflector trials but nothing seems particularly effective. With the Stuart Highway for instance, there are cattle grids every so many kilometres, but in effect, the main highway passes through grazing land with free roaming cattle and sundry wildlife and introduced critters like the camels, pigs and goats. Serious locals tend to drive things like utes or cab 4x4s, a Landcruiser or something, with big bad bull bars and a sporting arena's worth of lighting protruding from the top (Destroyer class spotlights for roo shooting are obligatory). Confederate flags are rare as hen's teeth here, but you might spot some good old bourbon paraphernalia. Mr Beam and Mr Daniels seem popular ones.