Despite being the chief executive of a firm employing almost 1000 staff, Mike Walsh still likes to take a hands-on role in the business.

The 51-year-old runs one of New Zealand's most recognisable companies - the VTNZ (Vehicle Testing New Zealand) network of warrant-of-fitness testing stations.

When the Business Herald arrived for a noon interview at the firm's Parnell site last week the boss was out on the forecourt, helping shift forward the cars awaiting inspection in the queue.

Walsh likes to avoid what he calls the "red zone" - when too many cars are backing up and customers have to wait longer than they expected. "They might get a bit of smoke coming out their ears," he said. "That's a continual challenge around customer service in the environment we operate in."

VTNZ is New Zealand's largest single provider of vehicle-safety inspection services, with 85 sites and 930 employees, 552 of whom are inspectors.

Walsh is proud his company opens about 900,000 Kiwi car bonnets a year.

Only one site is run as a franchise, and Walsh said the company had no plans to increase that number.

The firm started as a Government department in 1968 and morphed into a state-owned enterprise in 1994 before being privatised 12 years ago when the Motor Trade Association acquired it.

In spite of the recession, VTNZ's revenue has doubled over the past five years to reach more than $80 million in the year to last June.

Four new sites have been opened over the past 12 months and the capacity of many existing sites expanded.

But the firm's share of the warrant-of-fitness check market is only about 17 per cent and Walsh said there remained room for growth.

He said some consumers had a perception that VTNZ was more picky when inspecting cars than other outlets, such as mechanics.

"But our fail rates are lower than the garages," Walsh said.

The company is expanding its services to extra checks - at an additional cost - on things like water level, oil, engine noise and tyre pressure.

As many as 50 per cent of the cars on New Zealand roads were running low on oil, Walsh said.

"When you think about it, which service stations actually lift the bonnet and check your oil? All the service has disappeared from the forecourt."

Walsh knows quite a bit about the petrol industry, having been a director and retail operations manager of Exxon Mobil before joining VTNZ six years ago.

These days, he spends two days a week visiting vehicle-testing stations around the country.

"I spend as much time as I can talking to our people and customers."