For what it’s worth, and again this is anecdotal, but I have plenty of friends who’s modern cars also survived - so I don’t feel this article is accurate when the author sums up the reason these classics survived is because “they just don’t make them like the used to”
I would imagine it has much more to do with how this particular fire spread, and the tremendous high speed winds that drove the majority of the burn the first night. Sparks, embers, and flames were jumping and spreading at a tremendous rate as if they were looking for things that would burn - in this case the cars were less flammable than houses.