It’s a common sight during summer. It’s also a recipe for disaster.

I recently drove with my family from New Plymouth to Tāmaki Makaurau and, just like how I lost count of how many cows I saw on the way, I lost count of how many cars had a passenger sitting in a position that made me quiver and shake my head.

That particular position is when the passenger who called shotgun has their feet relaxing on the car’s dashboard or outside their window while the car is in motion.

I quivered because on first principles I can see how, if a car accident were to occur, being in that very position, like you’re chilling on a hammock, would lead to some disturbing, life-changing injuries. It’s not something you would catch me doing ever.

During this five hour drive, after seeing a fourth passenger with their feet on the dashboard going through Te Kuiti, I asked my husband, who’s been a doctor for 12 years, whether he had heard of patients presenting with injuries from sitting in this position in a car. Without hesitation, but also without any further explanation, he simply said yes.

Engineers and data scientists at the New South Wales Road and Maritime Services Crashlab demonstrated how dangerous this seating position is in 2017 at a purpose-built facility located in Sydney’s western suburbs.

The team conducted a crash simulation which had a Holden Commodore impacting a wall at 70km/h, resulting in the deployment of the front passenger airbag. The dummy passenger had its feet on the dashboard and the airbag pushed the dummy’s feet back into its face.

On reviewing their results frame by frame, the experts saw the seatbelt caused the bulk of the damage and having the feet up on the dashboard had caused the dummy to slip down underneath the belt, which meant the internal organs bore the brunt of the impact.

If that isn’t enough to convince you to quit the habit when jumping into the front passenger seat, read the story of Irish woman Grainne Kealy, who broke nearly every bone in her face in a car crash while her feet were on the dashboard. Kealy’s boyfriend’s Jeep hit a wall at 120 mph, causing the airbag under her feet to inflate and her knees slammed into her face. She is now left without a forehead after doctors were forced to remove it and suffered multiple facial fractures and a fluid leak from her brain.

Next time the sun tempts you to wind your window down for fresh air and you ponder putting your feet up to relax while sitting in the passenger seat, think about your lovely face and keep your feet on the ground.

This is Public Interest Journalism funded through NZ On Air.