Which vehicles are not allowed to use a road sign-posted like this?

The sign shown indicates that motor vehicles are prohibited in that area. In terms of German traffic regulations, this specifically means that cars and trucks are not allowed to enter the road postulated by this sign. Motorcycles might also be prohibited depending on local rules, but typically in this context, the primary focus is on cars and trucks.

The purpose of such restrictions can be for various reasons, including environmental protection, preserving pedestrian zones, or reducing traffic in congested areas. Understanding these regulations is essential for safe and compliant driving, ensuring that you respect local traffic laws designed to enhance road safety and urban management.