Unfortunately, I’m not familiar with iCar. However, my father owned an auto service shop when I was younger and I’ve been around the industry practically half of my life. I know the Automotive Service Excellence, or ASE Certification, is one of the most recognized within the Automotive Service Industry. You should be able to study and train online to prepare for the test. The website also offers practice tests which would allow you to gauge your knowledge before taking the actual exam.
Visit this website for more information: https://www.ase.com/
Hope this helps!