Hi there! The best MCAT study resources are the ones of the AAMC. It is, after all, the organization that administers the test, so you know you will be practicing with realistic materials. The AAMC offers question packs for each section of the MCAT, including two volumes for the CARS section, each containing 120 passages and questions. Practicing with these materials will allow you to gauge your true performance level and work to improve it before your test. If the passages you use to practice aren’t as complicated or challenging to read as those found on the actual exam, you will be developing your critical analysis and reasoning skills at a lower level, which will ultimately be detrimental to your MCAT score. This being said, take into account that these materials alone do not expose you to everything you need to be aware of. If you are only briefly exposed to humanities and social science texts through CARS preparation, for instance, you are far less likely to do well on CARS. Practicing with test materials only, limits your ability to become comfortable with CARS texts, BUT extending your practice to other, similar written materials will allow you to get additional growth in your critical thinking and reasoning skills. Consider reading about classic literature, journal articles, and other readily available texts like The New Yorker, The Economist, The New York Times, Humanities and Social Science Journal Articles, or even literary classics like Ernest Hemingway, Oscar Wilde, George Orwell, or Margaret Atwood. Whatever you chose, make sure you read diverse and challenging materials. Hope this helps!
