2016 hyundai equus - black soot being emitted from engine through exhaust system. very heavy deposits on rear of vehicle, sufficient to blacken clothes, discolor the vehicle, does not wipe off after a few days and chemicals must be used to remove. manufacturer says: "this is a normal byproduct of the gdi engine". see (pics) multiplying the number of hyundai vehicles in the u.s. by what i am seeing on my car, this could be a serious air pollution issue.