Two new studies demonstrate some major downsides to upsizing our cars
Our vehicles have never been bigger or heavier than they are now. Take the Ford F150 truck. Between 1991 and 2025, it got 75cm longer, 20 cm taller, and 483 kg heavier. But it’s not alone; the same trend of ‘supersizing’ can be seen all across the automotive market.
Larger vehicles – particularly sports utility vehicles (SUVs) and light truck vehicles (LTVs) – are growing in popularity at an unprecedented pace. Eight out of the top 10 passenger vehicles sold in the US so far in 2025 were SUVs or LTVs. In New Zealand, nine of 2024’s top 10 sellers were SUVs or LTVs (which are most often referred to as ‘utes’ here). Globally, SUVs made up 48% of new car sales in 2023; that’s up from 15% in 2010.
These supersized vehicles come with numerous downsides. The first and most obvious one is that those vehicles that rely on fossil fuels – which represent the vast majority of the fleet – are famously bad for the environment.
Road transport is responsible for 15% of all global CO2 emissions, and SUVs and LTVs play a big role in that. As reported earlier this year by the BBC, “If ranked among countries, the global fleet of SUVs would be the world’s fifth largest emitter of CO2, exceeding the emissions of Japan and various other major economies.” The International Energy Agency has also found that due to weighing 200-300 kg more, an SUV that runs on petrol or diesel emits 20% more CO2 than an average to medium-sized car. Given that CO2 is the main contributor to the warming of our planet, adding more SUVs to the fleet seems like a retrograde step.
Electric SUVs and LTVs aren’t entirely blameless. They, like all road vehicles, produce vast quantities of tyre emissions – tiny pieces of rubber and other materials that tyres release as they wear down. Tyre particles are known to enter our waterways, and the smallest of them can even become airborne. Once there, they pose numerous threats to human health and to the wider environment. Bigger, heavier vehicles tend to produce more of this particulate pollution.
Looking beyond the environmental impact of car-bloat doesn’t improve things.
In the past few weeks, I’ve come across two new research papers that focus on SUVs and light trucks. These studies come from entirely disparate fields and have no researchers in common – one study takes a traffic engineering viewpoint, and the other looks at human safety implications. Both come to the same conclusion: these large vehicles are having a negative impact on urban life.
Let’s start with traffic.
SUVs make road congestion worse
There are lots of reasons why traffic might be on the rise in your nearest city. Maybe your public transit mode is receiving less funding, or there is no safe way to cycle or walk into the center, forcing city dwellers into their cars. Population growth and urban sprawl also increase reliance on private vehicles. But a new study published in the journal Transportmetrica A shows that an increase in the number of large vehicles on urban roads is making traffic congestion worse for everyone.
To come to this conclusion, traffic engineer David Levinson (a Professor at the University of Sydney) and data scientist Dr Yang Gao (from City University of Hong Kong) looked at 25 years of traffic data from the Minneapolis–St. Paul freeway network. “We chose this network because the data has been available in a consistent database structure that’s open access and well-maintained, since the 1990s. That’s not something you can say for most highway databases,” says Levinson, speaking over Zoom.
Levinson and Gao focused on trucks – a class of vehicle that includes both SUVs and tractor-trailers. “Numbers of both of these vehicle classes have risen over time, but SUVs have risen at a much, much greater rate over the last 25 years,” says Levinson. “We were able to separate out how much of the rise was due to SUVs versus larger freight-carrying trucks, and then look at their impact on throughput.”
Throughput is defined as the maximum number of vehicles than can move through a lane in one hour – it’s a good measure of how traffic is flowing. In practice, this is measured by loop detectors embedded in the roadway. Levinson and Gao had access to daily traffic data from 564 loop detector stations across the freeway network between 1995 and 2019.
They found that, over the study period, average network throughput decreased from approximately 1850 vehicles per lane per hour to about 1600. At the same time, the number of SUVs on the Twin Cities’ freeways jumped almost tenfold, rising from 3.65% of all highway vehicles in 1995 to 30.8% in 2019.
There was a much smaller increase in the number of tractor-trailers on the roads during that time too, but statistical analysis of the data showed that their impact on traffic flow was dwarfed by that of SUVs.
When asked why SUVs reduce throughput, Levinson says, “Well, first there’s their physical size – they literally take up more space on the road, and it takes them longer to brake because of mass and momentum.” The behavior of other road users also plays a part, “Our data is too aggregated to show this specifically, but it is apparent that because they are taller, vehicles behind SUVs tend to give them more space, which also influences traffic flow.”
Once a lane reaches its maximum capacity, the addition of any vehicles will cause delays and congestion. If those additional vehicles are SUVs or LTVs rather than standard passenger cars, that will have a larger effect on congestion. “SUVs impose a greater delay on the vehicles behind them than do smaller cars,” says Levinson.
And that brings us to the second reason SUVs are a problem.
They’re more dangerous for (nearly) everyone
SUVs come with a perception of increased safety for occupants. The reality is less straightforward. Yes, in a head-on crash between a car and an SUV, the driver of the car is at a higher risk of dying, but because they are taller than cars, SUVs are more likely to roll over in any crash, which increases the risk of serious injury for occupants. Their stiff structure also means that in the case of an impact, SUV occupants will experience higher deceleration than in a small car, which can lead to injuries including concussion and even organ rupture. In addition, a growing body of evidence suggests that larger vehicles are associated with riskier driving behaviors.
Something there’s no doubt around is that SUVs and LTVs are statistically less safe for everyone outside the vehicle. And a new study from researchers at the London School of Hygiene & Tropical Medicine (LSHTM) and Imperial College London lays bare the scale of the danger they pose.
The team set out to answer two questions: (1) Do SUVs and LTVs cause more severe injuries to pedestrians and cyclists than passenger cars in road traffic crashes? (2) Is there any difference in outcomes for adults and children? They also wanted to use only real-world crash data – no lab-based tests or simulations.
To answer those questions, they carried out what’s known as a meta-analysis – effectively, a detailed review of existing studies, to find those with the most relevant, reliable data that can then be combined. Through the use of statistics, meta-analyses like this one can paint a much more coherent picture of a problem, and give a more precise estimate of its impact. 24 studies – the majority of which were based on US data – were included in this particular analysis, representing more than 682,000 real-world crash victims from the last 35 years.
They found that in a crash, pedestrians or cyclists struck by a SUV or LTV suffered more severe injuries than those hit by a passenger car. Incidents involving SUVs and LTVs also came with a significantly increased risk of fatality, too. Across all studies, they showed that a pedestrian or cyclist is 44% more likely to be killed if they’re struck by an SUV rather than a passenger car. The situation is even worse for younger victims – a child struck by a SUV is 82% more likely to be killed than a child struck by a passenger car.
LSHTM Assistant Professor Anna Goodman, who led the study, says, “Around the world, we have seen a huge increase in the sale of ever-larger cars. Previous research has found that this trend is substantially undermining progress towards net zero goals. Similarly, our findings indicate that this proliferation of larger vehicles threatens to undermine all the road safety gains being made on other fronts.”
Making them less attractive
The crash study also supports the decision by a growing number of cities to disincentivize the use of SUVs and LTVs on their streets. Paris tripled its parking charges for heavier cars in 2024, and a number of cities have introduced or are considering similar measures. Others are targeting the manufacturers directly. In the UK, Edinburgh and Sheffield have banned advertising of “high-carbon products” such as airlines and SUVs, comparing them to “today’s tobacco”. The Hague, Stockholm and Montreal have introduced their own ad bans, with other towns, municipalities, cities and territories hoping to follow suit. For an industry driven by selling a particular ‘lifestyle’ often accompanied by dramatic scenery, such bans can be very effective. This may explain why car manufacturers are doubling down in other regions. Between 2022 and 2023, advertising expenditure on SUVs rose by 29% in Australia, just as new fuel efficiency standards were announced. In NZ, Toyota spent $7.6m in three years advertising a single vehicle – the Hilux, its double cab ute.
“Cities and countries around the world are starting to introduce measures to discourage the use of these large vehicles, and our study strengthens the road safety rationale for this,” says Goodman. Levinson and Gao’s study arguably gives cities a traffic congestion-related reason for rejecting SUVs. And countless studies before these two have established the negative environmental impact of supersized trucks. Do we really want more of them on our roads?