You may have noticed — there’s a car-size inflation on Australian roads that some have nicknamed car “mobesity”.

Most SUVs and utes from a decade or two ago look small next to today’s models.

As we head for a fifth consecutive year of rising road deaths and what could be the worst year for pedestrian fatalities in nearly two decades, it’s time to look more closely at what this means.

We already know bigger cars cause greater impacts in collisions.

But what’s less discussed is whether driving one also changes how we drive – if larger vehicles make us feel safer inside them, do they also make us take more risks behind the wheel?

Four in five new cars sold in Australia are SUVs or utes – more than double the share of 20 years ago.

This isn’t purely consumer-driven.

With no domestic car manufacturing, Australia imports vehicles shaped by global production trends, many of which trickle down from United States policies that reward larger vehicles.

Two subtle US policy features explain why.

First, the “SUV loophole”: under US law, most SUVs are classified as light trucks, meaning they’re subject to less stringent fuel-efficiency and crash-safety standards than passenger cars.

Second, under US fuel economy rules, fuel-efficiency targets are adjusted based on the size of the vehicle’s “footprint” — the area between its wheels. In........

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