However, in some accidents it is less efficient, because there is a risk that the occupant slides out of the shoulder belt. This can occur in rollovers and to far-side occupants in side-impact collisions.

Of all life-threatening injuries to car occupants, about 10% are to the head in side-impact collisions and half of these injuries are to the far-side occupants. In vehicle rollovers, 10,000 people are killed every year in the U.S.

In many new vehicles, the occupants on the near side (the side that the occupant hits first in a rollover) will get protection from an Inflatable Curtain, in addition to the protection offered by the seat belt. For occupants riding on the far side it is imperative that they do not slide out of the seat belt.

The 4- and 5-point belts that are used in racing cars require both hands for buckling up, which would reduce seat belt use if they were to be introduced in regular cars. Autoliv's answer to the problem is a 3+2-point belt with a Side-Support Airbag (SSA) at the inboard edge of the seat back.

H.R.H. Crown Princess Victoria of Sweden testing the 3+2 point seatbelt and Side-Support Airbag during a visit to Autoliv.

The additional 2-point belt is attached to the upper edge of the seat and runs across the shoulder part of the existing 3-point belt. It is supplemental to the 3-point belt and can only be buckled after this belt is properly buckled. This means that people who do not use the new belt will always have at least the same seat belt protection as today, i.e. not considering the additional protection from the Side-Support Airbag.