The chief executive of Midas NZ says there will be unsafe vehicles on the road and people will need to do their own car checks as time between getting a new Warrant of Fitness is extended.

From next month, new cars will not be required to get their second WoF for four years, while vehicles aged between 4 and 14 years move from annual to two-yearly check.

For older cars from between the years 2000 and 2013 - they remain at annual checks, but for very old cars from before year 2000 these move from six-monthly checks to one year.

There are also increases to the amount people are fined for out-of-date WoFs.

Safety concerns have been raised across the industry with some expecting an increase in dangerous vehicles on the road.

Midas NZ chief executive Jason Wilson told RNZ’s Nine to Noon programme on Friday people will need to be more cautious and maintain their own cars in between the longer WoF checks.

"There is a gap right now on teaching kids, teaching people that have just left school how to maintain their vehicles.

"You maintain it, it looks after you and right now the change going from a year to two years, there's going to be unsafe vehicles on the road."

He said with an ongoing cost of living crisis, people were already putting off getting their WoF done.

"People need to buy food, need to pay their mortgage, but they're putting off their servicing right now. It's happening already."

He recommended all drivers should pay closer attention to issues that may not be very obvious at first.

This meant checking under the car for oil leaks and keeping an eye on tyres which Wilson said were likely the most important part of the car that needed to be kept safe.

"Check your tyres, check your windscreen, check your windscreen wipers, your mirrors, your lights... they're not big, but they're just helpful to get you through to the next warrant.

"Check for rust - everyone knows what rust looks like - and it's not good when your car goes rusty."

Wilson said self-checks meant the WoF bill might not be as massive, especially if the serviced checks are further apart.

This especially applied to those working in trades.

"These guys are on the road a lot and they're carrying a lot of gear with them... you need to get your car serviced. It needs to be regular."

He also explained that for the impact on mechanics "there's two sides to the coin".

"So there's going to be less checks, but when your car is not serviced after two years, that cost is going to be higher."

Motor Trade Association head of advocacy James McDowall told RNZ’s Morning Report programme in April serious issues increased on vehicles that were eight to 10 years old.

"That's when the fail rates on safety critical issues are around that 30-35 percent mark, and then it climbs from there."

McDowall pointed out that when the government consulted on the proposal, it had suggested increasing the WoF duration to two years for vehicles between four and 10 years old, but was now planning to introduce that for vehicles up to 14 years old.

"They've just turned around and come out with 14 years out of nowhere. That was not consulted on, and so that has come as a bit of a surprise."

In October last year, Associate Transport Minister James Meager said changes to the WoF and Certificate of Fitness A (CoF A) were a commonsense opportunity to modernise the country's vehicle inspection approach.

"New Zealand currently has one of the most frequent regimes globally. We want to make sure we're not placing unnecessary costs or time pressures on Kiwis, while still keeping everyone safe on the road," he said.