No. CR's reliability data come from its readers. That's why the

Educated people believe in books. Their buying decision is heavily influenced by CR. They are also the ones answering the surveys. So it's like a self-fulfilling prophecy.

Now, if the cars they buy are representative of all cars available, it does not matter to some degree. Although one can argue that educated people have different priorities and taste. But from above analysis, it's no way that the cars CR readers bought are representative of all cars.