Six car lengths is a good distance.
I always heard of the two second rule but I am not sure if that is law.
1m
one car length per 10 miles per hour
it is recommende to keep a gap of at least two seconds behind the car in front of you so the distance varies with the speed
A safe distance, there is no defined limits of this type as driving near parked cars is situational (at best).
One car length for every 10 miles per hour of speed.
Know your distance between cars, fire hydrants and railroad crossing. These are the most over looked.
The distance between two cars while driving should be at least 2β3 seconds of following distance under normal conditions. This allows enough time to react to any sudden stops or changes in traffic flow. It is important to increase the following distance in adverse weather conditions or when driving at higher speeds.
ten feet
100 fy
you should give at least a foot of space...