The interesting bit, this Tesla S was only 4 months old, parked in the garage. The car wasn't plugged in, so there's no 3rd party to blame on the fire. And it's in Toronto, Canada in the dead of winter.
Nothing for Tesla to point fingers at. Can't make up a story about road debris, ambient temperatures, electrical wiring or any of that.
From the article, it sounds like a classic lithium thermal runaway. Random, catastrophic system failure, which is inherent to having 1,000s of tiny lithium batteries packed together.