Hyundai Elantra N Owner's Manual page 79

Seats & Safety System
Air bag non-inflation conditions
In certain low-speed collisions the air
bags may not deploy. The air bags are
designed not to deploy in such cases
because they may not provide benefits
beyond the protection of the seat belts.
Front air bags are not designed to inflate
in rear collisions, because occupants
are moved backward by the force of the
impact. In this case, inflated air bags
would not provide any additional benefit.
3-50
Front air bags may not inflate in side
OCN7N031051L
impact collisions, because occupants
move in the direction of the collision,
and thus in side impacts, front air bag
deployment would not provide additional
occupant protection.
However, side and curtain air bags may
inflate depending on the severity of
impact.
OCN7N031052L
In an angled collision, the force of impact
may direct the occupants in a direction
where the air bags would not be able to
provide any additional benefit, and thus
the sensors may not deploy any air bags.
OCN7N031144N
OCN7N031137N