Final answer:
On slippery roads, it's recommended to double the following distance to at least 4 car lengths due to the increased stopping distance required on such surfaces.
Step-by-step explanation:
When driving on slippery roads, you should double your following distance to at least 4 car lengths. This increased distance is necessary because the distance necessary to stop a car varies greatly, depending on road conditions such as wet or dry pavement, as well as driver reaction time. Under typical conditions, a reaction time of 0.500 seconds is considered, but on slippery roads, both reaction time and braking distance can be affected, extending the distance needed to come to a complete stop safely. It's important for drivers to take these factors into account to maintain safety on the road.