There is the question of what we are trying to optimize for. If you are trying to attain maximum safety for a belted passenger, then no, current passenger seat

There is the question of what we are trying to optimize for. If you are trying to attain maximum safety for a belted passenger, then no, current passenger seatbelts are not optimal. This is clearly evident from the far better seatbelts and driver safety devices used in motorsport. Current seatbelts represent a tradeoff between safety if you use it, and how annoying they are to use (and therefore, how likely people are to get annoyed and not use them).