They say at least three drivers were caught doing over 200km/h in a 120kph zone, the fastest doing 224km/h.
In one case a driver was arrested doing 213km/h in a 100 kph zone. Others were booked doing 175km/h and 165km/h in the same zone.
The quieter roads appear to be encouraging daring drivers to ignore the rules.
One social media poster claimed even trucks were pushing the limits on the province’s roads.
“The N12 to Emalahleni is impossible. It is virtually impossible for someone doing 120 to pass a truck,” he said.
Vehicle-tracking company Tracker said vehicle activity dropped by 20% just before the lockdown, and plummeted as low as 75% after the lockdown came into force.
Traffic volumes have begun picking up since level 4 came into effect.