Thirty-six vehicles have been ordered off the road in Invercargill as police target "skid meets" around the city.
Senior constable Paul Moylan says Operation Hoon honed in on drivers who regularly do a lap of Invercargill's CBD before going to organised skid meets in rural locations.
The police took advantage of laws allowing for vehicles to be inspected if they were stopped within five kilometres of a VTNZ test site.
Myolan said an extreme example of the unsafe modification of a vehicle was the use of a pair of jandals as suspension bump stops.
Southern District Road Policing Manager Inspector Craig Brown said" "These drivers pose an unnecessary risk to everyone on the road through their behaviour and the state of their vehicles.
"To get this many unsafe cars off the roads over just two evenings is a great success for our teams, and goes a long way in making sure we can keep the roads safer, and help other motorists feel safer too."