On impact, an airbag takes just 100 milliseconds to deploy, and it does so at a speed of more than 300 km/h. That’s fast – even V8 supercar drivers rarely reach these speeds.

With most passenger airbags installed in the dashboard, it becomes pretty easy to imagine how putting your feet up can have disastrous effects in a crash. See for yourself – the below footage was captured by engineers and data scientists at Road and Maritime Services Crashlab in Sydney last year.

As the Holden Commodore collides with the wall at 60km/h, the front passenger airbag deploys and pushes the crash dummy’s feet back into its face.

Some of the injuries a passenger can sustain in this situation include a ruptured bowel, torn aorta, brain damage and possibly death.

RAA’s motoring expert Mark Borlace says the shocking video demonstrates how passengers who put their feet on the dash can increase their risk of serious head and chest injuries.

“Airbags are designed to protect you, but in this case it can cause more damage than good, as it propels the passengers’ legs back into their head and chest,” Mr Borlace says.

The seatbelt can also lose its effectiveness when a passenger’s feet aren’t positioned firmly on the ground, which is why Mr Borlace says passengers need to be more educated on good car posture.

“Airbags and seat belts only do their job if passengers and drivers do the right thing,” he says.

“Seatbelts are designed to hold the skeleton in place, but that’s not what happens when a passenger’s feet are propped up on the dash. The belt slips from the hips onto the soft part of the stomach where the vital organs are, which can sustain significant injury.”

Our advice? Next time you’re on a long car ride and find yourself squirming in your seat, stop the car, get out and stretch properly.