Anna Parsons (18) and Dayna Dodd (17) are absent.
The group organised the mural with help from Alexandra youth aid officer Garry Milford.
Depicting a black road with white centre lines and red and white lettering reading "It's Not Just Your Life", the mural is designed to deter people from driving after drinking at licensed premises on site.
Dunstan's SADD group started the mural a few months ago, and planned to finish it during the week after having taken time off to sit exams.