Unconscious cat

I was walking in an open car park one and I passed this white cat that was lying on a black car.

The cat was extremely exhausted that even though there was so much noise it hardly stirred! I was getting rather worried in case the cat had had a heart attack and was lying on its side. It is not normal that cats sleep on their sides. Fortunately I saw the cat was still breathing.

Here are the photos. Does your cat sleep on its side?