Hello Lauren,
The timing can be tricky with CARS passages! We often think most of our time goes into reading the passages but in reality we waste most of our time answering the questions! Try not to get bogged down with a tricky question and waste lots of time- remember, they are all worth the same amount of points. It should take you on average 4 minutes per passage, then one minute for each question (this is an average- some will be shorter some will be longer!)
I would recommend doing the passages with the timing right away to get you accustomed to the skill of CARS. Try to answer each question but focus on not spending too much time on one. If you do not have time to finish it within the time frame, you could just do it at the end and time for that specific passage/question.
Hope that helps,
Kennedy