Bigger cars don’t make occupants safer, but put others at higher risk

Heavier cars offer limited safety gains for occupants, but do put other road users at higher risk, according to a new study from the US-based IIHS.

The conclusions of the research challenge perceptions of occupant safety that are commonly cited as a reason for people buying larger cars and SUVs.

According to the study, cars under the average fleet weight (of 1800kg in the US) see improvements in occupant safety from increased weight, but cars over the fleet average weight see no significant improvements from the same. Put another way, the more similar the weight of two cars, the safer the occupants will be in the event of a crash.

However, the key point here is that car drivers are not the only road users, and heavier cars like SUVs and pickups are significantly more dangerous to children, pedestrians, cyclists and people wheeling.

Sam Monfort, a senior statistician at IIHS and lead author of the study, said: “What this analysis shows is that choosing an extra-heavy vehicle doesn’t make you any safer, but it makes you a bigger danger to other people.”

Combining these two facts leads to the conclusion that where cars are necessary they should be as small and light as possible. Not only would this protect those inside the car (from being hit by a larger SUV) but it would protect vulnerable road users, too.

Cars in the UK became 400kg heavier on average between 2016 and 2023, partly because of increasing SUV use and partly due to electrification and inclusion of more safety features that add to total vehicle weight.