Final answer:
The grape used in many Banyuls and Roussillon for making vin doux naturels is the Grenache Noir grape.
Step-by-step explanation:
The grape used in many Banyuls and Roussillon for making vin doux naturels is the Grenache Noir grape. Grenache Noir is a red grape variety that is widely grown in the Roussillon region of France. It is known for its high sugar content, which makes it ideal for producing sweet fortified wines like vin doux naturels.