It is wrong to suggest that a rear seat passenger is protected by the front seat in a collision. In an impact, all occupants move toward the point of impact, which is not necessarily at the front.
Moreover, in a front-end collision, it is very likely that your knees will hit the front seat first, which may cause your body to rotate.
As a result, you could end up on the front seat in a fraction of a second and hit solid objects, or even the driver or passenger, and kill them.
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