I thought IREX was pretty easy (scoring a hunjy)... compared to CPL.. maybe because we had more time to study.. For CPL we had a few exams booked in for each day due to our tight flying schedule at the time. My advise is to get your hands on as many past papers as possible, and to know your AIP back to front.. or at least where to find everything and understand what it means. If you think you've found the answer always read a few pages either side to see if there are any conditions Eg the HIAL not available vis. Also questions refering to instrument plates - scan the entire plate for relevent info, including the notes at the bottom. Remember for your regs, there's the index to help you, and tag the areas which you can't find in the index.
P.s i dont think i used CAR once in IREX
And 4spooled.. the answer is definately D