Why does alcohol interfere with the ability to drive a car?

Alcohol intake reduces the working capacity,  memory, visuospatial capacity which is associated with multiple brain lesions.

Explanation:

A person will not able to see signs and signals clearly that may lead to accidents. Besides being illegal, drinking and driving can be fatal as it results in impaired vision. Senses don't work properly because of which the person loses control over the vehicle and falls off or can collide with something dangerous.

As his reflexes become slow, he is not able to react aptly in difficult situations.  Alcohol intake also increases blood pressure, chances of stroke and cirrhosis of the liver. If these conditions occur on roads while driving, it would be harmful for self as well as others travelling on roads.