The 2015 book set is just fine, if you don't mind PDF and don't want to spend the money then you definitely don't have to. The content doesn't change between editions just mostly wording and arrangement. I don't recall Kaplan having much weaknesses in the content review area I used kaplan and liked their books, there will be people who tell you otherwise. If you have a decent background in the subjects then Kaplan is good. I never used the CARS book except for the passages found in there, studying CARS for me was doing 3 timed passages every single day until I became proficient at it. Make sure to do lots of practice questions this is especially important for CARS.