The tether anchors move to the back of the vehicle seat for 2018 (earlier model years they were on the floor in the cargo area). There is now long seat belt hardware for 2C on the side where the lap belt is anchored.
2013 saw the reintroduction of the Elantra GT as a hatchback (not the Touring wagon of previous years). The tether anchors are on the cargo floor. The seat belt in 2C is now better for car seats – as it no longer has the bulky additional hardware on the side where the lap belt is anchored (that it had in previous years, and sadly regains for 2018).
The Elantra hatchback stopped being produced in 2006, and in 2009 Hyundai re-introduced a wagon option of the Elantra. There are now head restraints for all 3 seats. In 2012 the head restraints for 2D & 2P were changed and no longer overhang the seat back (like they did before or still do in 2C). The buckles are all rigid and flush with the seat cushion.
The tether anchors, starting for 2004, are now on the cargo floor. The back seat is otherwise identical to the 2001-2003.
The Elantra was redesigned for 2001. It now for the first time has lower anchors (in 2D & 2P), a shoulder belt for 2C, and head restraints for 2D & 2P. There is still no head restraint in 2C.
The tether anchors for 2001-2003 are located behind what the manual refers to as “blanking covers” (circled in green in the picture below).
The 2000 back seat is identical to the 1999 – except starting for 2000 there are tether anchors for all 3 seats (no need to retrofit anymore!).
For the wagon, there are cargo hooks very near the tether anchors for 2D & 2P… don’t get confused – make sure you use the tether anchor (circled in green). 2000 was the last year for the Elantra wagon (a 5 door hatchback would be made starting in 2002, however).
Tether anchors can be retrofitted in these 1992-1999 vehicles – there are weld nuts in the shelf below the rear windshield specifically for a tether anchor hardware to be screwed into. Check your glove box for the tether anchor retrofit kit. This model year range has a lap belt in 2C and no head restraints in any of the 3 seats in back.