Answer:
It definitely isn't good if a cat drinks antifreeze. Even a small amount could damage the cat's organs and possibly give it mental problems. Antifreeze contains ammonia, so naturally attracts animals as it smells like another animal's urine. An animal will naturally sniff or perhaps lick liquids containing ammonia. It is also said that it may taste sweet as well.
If you have antifreeze, I advise you keep it sealed tight and out of reach of animals and children. A moderate amount of antifreeze could kill a cat or dog. In fact, this is a big killer of animals.