Is there a specific traffic law in Spain that officially bans driving while wearing a winter coat, and can you be fined for it?

A)No, it is completely legal under all circumstances, and police officers are never allowed to fine a driver for what they are wearing.
B)Yes, there is an official "Winter Clothing Ban" in the traffic code, and it carries an automatic 100-euro fine.
C)No, there is no direct ban, but you can still be fined up to 200 euros if the coat is so bulky that it restricts your movements.Correct
This is the trickiest part of the law. While wearing a coat itself is not explicitly banned, restricting your physical mobility while driving is a punishable offense under Article 18.1. If your jacket is too thick and stops you from steering safely, you can face a fine between 80 and 200 euros.