Luxury car brand Porsche has accused the Northern Territory Government of running a "nanny state" for removing controversial open speed limits on some stretches of road.

Key points: Parts of NT have been speed-limit free

Parts of NT have been speed-limit free Chief Minister Michael Gunner says that will change by the end of the year

Chief Minister Michael Gunner says that will change by the end of the year Mr Gunner says it's about saving lives on Territory roads

The NT, along parts of the Stuart Highway between Alice Springs and Tennant Creek, has been the only part of Australia where drivers can travel as fast as they want.

New Chief Minister Michael Gunner said that would change by the end of the year after he implemented his pre-election promise of removing the unrestricted speed zones.

That drew anger from German car maker Porsche, which said it would damage the NT's reputation.

"We've done a pretty good job of killing off the local car industry, the manufacturing of local cars in Australia, and now it seems the Northern Territory Government's doing its best to deter international car companies from coming to Australia to spend money and invest in the local economy," Porsche's director of public relations Paul Ellis said.

Mr Ellis said it was a significant blow to the company, which used the roads to test its cars and film advertisements.

"It's an entirely politically motivated decision," he said. "There's no logic. There's no sound reason behind it."

Surgeons opposed more unrestricted zones

Mr Gunner said it was about saving lives on Territory roads.

"We have made that decision for safety, on the basis of advice from doctors," he said this week.

In response, Mr Ellis said: "Speed does not kill, bad driving kills. And it's just a shame we've taken a nanny state approach."

The Country Liberals promised to expand open speed limits if they were voted back in, but Labor pledged to scrap them altogether.

They had the support of the Royal Australasian College of Surgeons (RACP), who argued against the expansion of unrestricted zones, warning that with higher speeds comes a greater risk of injuries from road accidents.

This week Mr Gunner said car companies could still apply to do testing at any speed, via the Control of Roads Act.

"We can allow for permits for testing in the Territory," he said.

"This has happened in the past with Ford, Bentley and Top Gear."

Mr Gunner said his Government would write to all companies informing them of the decision to remove open speed zones.