UN Regulations Nos. 49 and 83 include provisions for a “driver inducement system” that alerts drivers of low reagent levels (urea, etc.) critical to correct emissions control performance and eventually prevents vehicle operation if the reagent tank is empty. Under UN R49 (para. 5.2), rescue, police, and other emergency/special use vehicles are exempted from this requirement. This proposal would extend the same treatment under UN R83.