Consuming what substance before or while driving, can make you unfit to drive?

You answered correctly. Cocaine, alcohol, and hashish are all substances that impair your ability to drive safely. German traffic law strictly prohibits driving under the influence of any of these substances, as they can reduce attention, reaction time, and judgment. Being unfit to drive because of any intoxicant is a serious offense and can result in severe penalties, including loss of your driving license. In any situation, never drive after consuming drugs or alcohol to ensure safety for yourself and others.