In our opinion, drift car aero is very superfluous and mostly limited to cosmetics. When you look at smoke patterns around the rear wing of drift cars, it is apparent that when sideways, the flow is very turbulent around the wing, making it almost totally ineffective.
Basically, in a drift car, the wing does not really make much downforce due to disturbed and angular airflow, but it acts more like a stabilizer as the drag it creates moves the car's center of pressure rearward, like the fins on an arrow.
The APR swan neck rear wing mounts on Dai's were strengthened over the previous year and FD required tethers hold the wing in place in case it gets broken off by contact. For 2018, FD has changed the rules, banning wings from all courses except Road Atlanta and Texas. At these tracks, contact with a wall is unlikely. The ban is due to fears that flying broken wing parts could injure a driver, course worker or fans.
For all the tracks where wings are not allowed, Dai will be running a bigger rear deck spoiler. For this team, the wing is mostly cosmetic as there is not much of a technically measurable advantage.
However, the splitter is not even close to being as effective as it could be because of air leaks between it and the bumper and a lack of a belly pan. These things would make the front of the car too difficult to repair, especially in a 5-minute competition timeout.
In addition, the pumping action of the rapidly spinning rear wheels is considerable to the point where they reverse the airflow through the heat exchangers, despite the huge electric fans sucking air through them.
We know this because high volumes of tire smoke pour out of this scoop when the car is at speed with the wheels spinning! Aero is not intuitive!