Tourists caught driving their rented cars dangerously on New Zealand roads are having their keys confiscated.

After receiving *555 complaints, police are stopping the cars and, after assessing their driving behaviour, calling rental operators to ask if they want to cancel the car hire contract.

If the company agrees, police confiscate the keys.

About 10 foreign drivers in rental vehicles had their car keys confiscated at the roadside in the past six months, after police received reports of potentially deadly driving manoeuvres, the Rental Vehicle Association said.

One was an overseas driver who performed several high-risk passing manoeuvres.

In another, a tourist driver could not keep on the proper side of the road.

Foreign drivers hit the headlines during the holiday period.

Two tourists died when their car smashed through the Wanganui bridge railing on the West Coast.

A German national caused a crash in Southland on Boxing Day, killing a Chinese student living in Invercargill.

Association chief executive Barry Kidd said cancelling the contracts may have saved lives.

"This is with extremely risky behaviour, where if they had not been stopped an accident is likely to have resulted.

The move is part of an NZ Transport Agency (NZTA)-led project called Visiting Drivers.

In most cases where keys were confiscated and the rental company phoned, at least three *555 calls had been made, Kidd said.

During the summer peak season, about 100,000 vehicles were rented each month. The majority were problem-free, Kidd said.

Nationally, tourist driver "at fault" crashes were decreasing, with six per cent of injury crashes involving tourist drivers, NZTA's International Visitors Research Report said.

The exceptions were Southland and Otago.

Between 2009 and 2013, there were 493 crashes in the area. In 409 of those, an overseas driver had a degree of fault, NZTA said.

Google a factor in tourist crashes?

New Zealand Transport Agency has convinced Google to change its travel algorithm for the treacherous tourist route between Queenstown and Milford Sound.

Agency southern director Jim Harland said between 2011 and 2014 there were 69 tourist-at-fault crashes between the two destinations, two of which were fatal.

Harland said Google's travel time for the 288 kilometre trip was unrealistic - 50 minutes faster than the New Zealand Automobile Association travel time calculator.

"You would have to driving pretty much at the maximum legal speed limit, not stopping at all to take photos, not get stuck behind traffic or a truck to make it," Harland said.

After "a few negotiations" with Google, the travel time was changed to three hours and 44 minutes, still 30 minutes shorter than the AA's estimate.

Tourist crash hot spot

Otago and Southland tourist "at fault" crashes 2009-2013

493 crashes, 409 degree of fault of overseas driver.

14 fatal crashes, 81 serious injury crashes, 314 non-injury crashes

66 per cent from right-hand driving countries.

75 per cent were during the day.

56 per cent were on bends.

66 per cent involved male drivers.

9 per cent included alcohol as a factor

75 per cent were on a 100kmh road

Social cost averages $31m per year.

* NZTA International Visitors Research Report and Overseas Drivers Part 1 Otago and Southland report.