HWP are usually SS or XR6 Turbo, so not quite as slow as a bog stock commodore. Have seen cops at the bottom of that hill in the past.
I was even driving a Nissan Patrol down there one day, and sitting on 110 exactly - the cop, hiding in the bushes at the bottom of the hill, gave me a dirty look, even though I'd done nothing wrong. Seems easier for NSW Police/Govt to just punish you when you've done wrong, rather than being visible and preventing accidents in the first place (by, say, oh I dunno... mandating defensive driver training)..