When Cars parked on the side of a highway at night should show?

When cars are parked on the side of a highway at night, they should have their hazard lights activated to alert other drivers. Additionally, if possible, placing reflective triangles or flares behind the vehicle can enhance visibility. It's important for the parked vehicle to be positioned as far off the road as possible to ensure safety. Lastly, drivers should ensure that any passengers remain inside the vehicle until help arrives.