noun
license plate beginning with 8 (used by emergency/service vehicles)
Refers specifically to the license plate classification system in Japan where vehicles with plates starting with 8 are designated for special use, such as police cars, ambulances, and fire trucks.
８ナンバーの車両は緊急時に優先される。
Vehicles with 8-number plates are given priority in emergencies.
noun
special-use vehicle (e.g., police car, ambulance, sprinkler truck)
Colloquial extension of the license plate meaning; used to refer to the vehicles themselves, especially in casual conversation.
あの８ナンバー、サイレン鳴らして走ってたよ。
That special-use vehicle was running with its siren on.