CNG fueled buses are labeled with a __ diamond-shaped sticker located on the front and rear bumper.

CNG (Compressed Natural Gas) fueled buses are labeled with a blue diamond-shaped sticker located on the front and rear bumper to indicate that they use natural gas as a fuel source. This color coding is part of the system used to identify the type of fuel being utilized by vehicles, particularly for emergency response purposes. The blue color helps first responders quickly recognize the presence of CNG in the event of an incident, allowing them to take appropriate safety measures when working around these vehicles. Proper identification through this labeling is crucial for ensuring safety during emergencies involving CNG vehicles, as it alerts responders to the specific hazards associated with this fuel type.