A crackdown on boyracers in Christchurch on Saturday night was a success, police say, with two arrests, seven cars impounded and 156 notices issued to vehicles that didn't comply with regulations.
Police beefed up their presence on city roads targeting speed, drink driving and disorderly behaviour.
Acting senior sergeant Kerei Gray said two men were arrested for willful damage and assault, and two others charged with excess breath alcohol.
He said cars were impounded for racing, being unsafely modified and having suspended or forbidden drivers behind the wheel.
Mr Gray said police will continue to run operations to deter boyracers in Christchurch.