Which scenario is an example of a temporary substitute vehicle?

The scenario where a mechanic loans a car while your own is in service best exemplifies a temporary substitute vehicle. This situation demonstrates a direct and immediate need for alternative transportation while the primary vehicle is unavailable due to repairs. The loaner from a mechanic is specifically provided for a limited time and is directly tied to the service being performed on the owner's vehicle.

This concept aligns well with how temporary substitute vehicles are understood in the context of insurance and auto usage – they serve to fill the gap while the original vehicle is out of commission. Other options may involve similar concepts of borrowing or renting vehicles, but they do not specifically tie back to a scenario of automotive service and repair, which reinforces the understanding of the temporary need.