Key Points:

Scores of cars are being taken off the road from boy-racer hotspots as police crack down on illegal street racing.

Storage depots in the boy-racing meccas of South Auckland, Tauranga and Christchurch are crammed with cars impounded in swoops by police and other authorities.

South Auckland police say they have been seizing more than 50 cars a week since tougher legislation came into effect in May 2003.

The law gives police the power to automatically impound cars for 28 days if they are being driven with unnecessary speed or acceleration or are doing burnouts.

In the past week, Counties-Manukau police seized 76 vehicles. Most were not impounded under the 2003 legislation, but police say cars are often caught during the crackdown on boy-racers.

In Canterbury, police seized 30 vehicles during an operation on Friday and Saturday nights, and in Tauranga, police have made 798 prosecutions for "boy-racer offences" since January 2005.

The Waitemata police district, which covers North Shore, Henderson and Rodney, has impounded 933 vehicles - 46 a week - this year.

Police say the legislation is working well, despite criticism after the death of 20-year-old Scott Finn at an illegal car race in Tauranga on Saturday that not enough is being done.

Sergeant Stu Britnell, the officer in charge of vehicle impounding in Counties-Manukau, said that "up until last Sunday, we had 965 towed in this year".

Most cars were seized from people who drove while forbidden, disqualified or suspended.

Of the 76 vehicles impounded in the week to yesterday, only three were involved in illegal boy-racing.

But Mr Britnell said the law changes had given police more flexibility in getting people off the roads for offences less serious than the previous options of reckless or careless driving.

It also helped to make cars roadworthy, as drivers took necessary remedial action after having to "buy" their car out of the impound yard, he said.

Some cars had been taken in more than once and in one case, a family car had been impounded four times, Mr Britnell said.

Of the prosecutions in Tauranga, 274 were for unauthorised street or drag races, or "sustained loss of traction" - skids and burnouts.

More than 300 vehicles have been impounded.

A bylaw imposing rolling street curfews is expected to be adopted in Tauranga after the weekend death.

Bay of Plenty road policing manager Inspector Kevin Taylor said the boy-racer legislation was "a very effective tool" that police used often.

But they also supported the introduction of bylaws such as that being proposed in Tauranga.

"Under the boy-racer legislation, we have to wait until they've committed an offence, so we play cat and mouse," Mr Taylor said.

"With the bylaws restricting access to a place, we don't have to wait for them to do anything wrong - just being there is a breach of the rules and we can move them on."

Of the cars seized in Canterbury over the weekend, 26 were taken because of unpaid fines and the rest were involved in boy-racer offences.

Canterbury's road policing manager, Inspector Derek Erasmus, said his district had changed its focus on seizing cars in the past few months.

Instead of taking them for 28 days under boy-racer legislation, police took bailiffs with them on operations and if drivers had any outstanding court fines their cars were taken by the courts and later sold.

"A vehicle that's been seized for unpaid fines might also have been subject to a boy-racer offence, but we bow to the court and say, 'While we can seize this car for 28 days, we are going to let you have it because you are going to take it and sell it'."

Mr Erasmus said police had seized 200 cars for the courts in the past couple of months. That compared with 200 last year.

The head of Tauranga's strategic traffic unit, Senior Sergeant Ian Campion, said boy-racers would continue to feel the heat from police as long as they engaged in illegal behaviour. "There will be no let-up by police on this group of people."

He supported the bylaw, saying police needed more power than the boy-racer legislation gave them.

"The legislation is a good tool to use. We just need more tools in our toolbox."