Joined: Feb 2009
Posts: 765
What the poster above said, the 'marks down' or demerits are key. When I took it, you were allowed to make more mistakes on class 5, then class 4. For class 4, they want to really FINE TUNE your driving skill and be more defensive on the road as you will be in traffic a lot more than class 5 driver.
I think I was allowed or 20 or 25 demerits to pass, whereas when I got my class 5, it was like about 40. Usually 5 point demerit mark is subtracted for every minor mistake unless you do something seriously wrong like rolling through stops, etc., where that can cost you all your points in one shot.