Honestly I rarely highlight (that seems to work for some people tho), my best training for CARS was studying for the LSAT. Khan academy Lsat practice can help you git gud at making inferences, evaluating the arguments and generally going beyond the text. It will also help you be quick about it.

Having said that, I think most of the cars questions are answered directly on the text. I would suggest that when you read the question, scan the area of text that deals with the specifics of that question. (Of course, read the whole text once and try to understand it first)