A number of vehicles have been detected as being modified in Derry City and Strabane.
Over 20 fixed charge penalty notices were issued at the weekend.
The Moor and Waterside Neighbourhood Policing Team carried out a joint road safety operation with the Driving and Vehicle Agency at the weekend.
During this, 18 vehicles were inspected, and close to two dozen fixed penalty notices have been issued in respect of vehicles being driven in a dangerous condition.
Some examples included the rear springs of one vehicle that fell out when the car was raised on the testing ramp.
In others, there were corroded brake pipes and tyres worn down.
A number of vehicles were detected being driven with windows that had excess tint, which Police say greatly reduces visibility, especially at night time.
One car had fuel leaking from the engine.
Three vehicles stopped were being driven without a valid certificate of insurance.
The PSNI say enquiries are ongoing.
