Sounds like an AC-DC album, but in the colder areas like the Southern Highlands, this can mean danger to drivers. Black ice is a thin layer of ice than forms on the road surface. Although the ice is not black it is transparent and the black road surface can be seen through it. The ice forms a layer which causes the car to loose traction. It often forms on shady patches where the heat has not defrosted the ice. Be aware of these areas and slow before coming into them. If you hit black ice it can cause the car to slid, do not brake or accelerate this will cause further problems. By decelerating the car can gain traction, depending on the speed you were traveling. Do not over respond. Gently steer the car as it slows. Prevention is better than cure , SLOW DOWN in sub zero temperatures and be aware of these high risk areas.