Without a seatbelt, in a crash at 30mph, you will be thrown forward with a force of between 30 and 60 times your body weight.
Seatbelts significantly reduce this force and consequently the risk of serious injury or death.
Front seat passengers are likely to be thrown against the windscreen and suffer severe head injuries.
Rear seat passengers who are not wearing a seat belt may be thrown forward and hit their head against the driver or front seat passenger, causing severe head injuries to themselves and the people in the front seats.
On-line crash simulator
Visit the crash simulator website to simulate a crash and the effect on car occupants not wearing a seat belt.