Alistair Woodward was a teenager last time big cars ruled the road.

“I remember in the 1960s those big, clunky, wide Cadillac-style cars. All the Fords and Holdens followed suit,” says Woodward, now an environmental health researcher and professor at the University of Auckland. The cars were wide and long and featured heavy iron and chrome parts. Seatbelts were optional - if they existed at all.

In the following decades though, the profile of cars began to change.

The development of the hatchback was “revolutionary”, as cities grew and a commuting lifestyle became common.

And then sometime around the early 2000s, the dial turned again.

Historical fleet data provided by the Transport Agency shows that in the last two decades, the fully-laden weight (known as the gross vehicle mass) of the average passenger vehicle in New Zealand has increased by nearly 300 kilograms, from 1783kg to 2079kg: the equivalent of something like a Mitsubishi Galant being replaced with a Nissan X-Trail.

That’s despite continued efficiencies in the design of cars, including using lighter materials. Once the preserve of rural communities or weekend warriors, SUVs and utes are now ubiquitous on New Zealand roads. It’s not just an illusion: we’re spotting them more often because there are, in fact, more of them.

When David Crawford started out as head of the Motor Industry Association a decade ago, the most popular type of car sold in New Zealand was a ‘medium-sized car’ - a sedan, or something like it; a car like a kid might draw.

Crawford attributes the soaring popularity of SUVs and other larger vehicles to style, in part, but also the convenience of some features. No, you might not need four-wheel drive in the city – but there are other drawcards.

“Don’t underestimate the creature comfort of being able to get in and out of those vehicles easily,” Crawford says. The higher frame of an SUV also makes it easier to load things into without having to stoop: groceries, the baby.

Stuff’s analysis shows that, per thousand people, predominantly rural areas are still buying more utes than city-dwellers. But the gap has been closing for the last decade, and for every ute in a ‘district’ council area (which largely equate with non-urban parts of the country) there are now 1.6 utes in ‘city’ council areas.

We’re adding more stuff to cars - some of it necessary, like safety features and technology to improve the cleanliness and efficiency of petrol vehicles; some of it creature comforts, like electric windows and cup holders. Batteries in hybrid cars add significant weight to some models. But the simple explanation, both Crawford and Alistair Woodward say, is that cars are just bigger.

“The size is obviously going to increase the weight,” Woodward says.

“You look at the wheels that are on those utes. You wouldn’t have seen those outside of a farm paddock 20 years ago and there’s no practical use for them in the city.”

Woodward says larger vehicles create an obvious problem: they produce more carbon emissions on average than smaller vehicles.

Data from both the Transport Agency and the Motor Industry Association show that average carbon dioxide tailpipe emissions for new vehicles, as reported by manufacturers, have been steadily trending down over the last 15 years.

Woodward says what is more important, though, is the overall emissions New Zealand’s vehicle fleet is producing. There are over two million more vehicles on New Zealand roads now compared to 20 years ago, outpacing population growth.

“It’s not the CO₂ per vehicle per kilometre [that matters]. It's the CO₂ emissions total,” Woodward says. “So while car sales go up and the proportion of larger vehicles goes up … transport emissions contribute more to the carbon budget.”

Real-world emissions from petrol vehicles may also not be decreasing as quickly as manufacturer data suggests. A 2015 Transport Ministry research paper found that the gap between reported emissions and (higher) real-world emissions had increased, to a 19 per cent gap on average for light vehicles.

Research Woodward published with his colleagues earlier this year also looked at the safety profile of larger vehicles, using data from a joint Australia-New Zealand crash database published by the Monash University Accident Research Centre.

“The two measures of safety are what’s called ‘crashworthiness’, which is the likelihood that the occupant will be seriously injured or die in a crash, and ‘aggressivity’ - the likelihood that someone outside the vehicle will be seriously injured or die if involved in a crash with the main vehicle,” Woodward says.

Among recently-manufactured larger vehicles, crashworthiness was better than average. “If you are the passenger or driver of one of those vehicles, you’re less likely to be killed in a crash than if you were in a lighter vehicle.”

But the calculation flips for people outside the main vehicle.

Vehicle mass contributes but so too does the design of larger vehicles, Woodward says, particularly for four-wheel drives and utes that are designed to tow large weights and travel across rough terrain.

“These vehicles sit on a rigid truck chassis. It doesn’t absorb energy if you run into it… You compare that with the front end of a car, which is quite carefully designed to crumple and protect both parties.”

David Crawford says rapid advances in technology - such as blind spot monitoring and autonomous emergency braking - are improving the safety of the newest vehicles for both those inside and outside the car, regardless of vehicle size.

In a collision though, “aggressivity does become a problem” because of the sheer weight disparity.

Can the worm turn again, as it did in the 1970s?

Crawford says more recent monthly sales show a voracious appetite for ‘small’ SUVs - indicating that it’s the features and style of those vehicles that appeal to many people, rather than sheer size.

He believes the government’s recently announced Clean Car Programme - the ‘feebate’ scheme - will nudge consumers when fees kick in for high-emissions vehicles next year, along with still-spiralling petrol prices.

Woodward puts the original rise in larger vehicles down to “weak regulation and savvy marketing” and says the fluctuating trajectory of car size and weight through history shows it’s possible to reverse recent trends. “I hate the idea that this is a culture war between people who hate utes and people who love them.”

He agrees with Crawford that signals from the top could help: “If the Government makes its intentions clear then the industry will follow.”

^{Source: Vehicles and statistics depicted are based on models that are close to the average passenger vehicle weight for 2000 and 2020. Data is sourced from NZTA/Waka Kotahi, rightcar.govt.nz, carsguide.com.au and encycarpedia.com}