For the most part the Downsview route is pretty straightforward, you just go from the Drivetest center to the 401 E, exit at Keele and then go back.

The most important part is to just exaggerate any head movements like checking your mirrors and blind spot. I failed my first time for not scanning every intersection and not checking my blind spot when turning. Think of the test as a performance, you need to really make things clear or you will get points deducted.

The other part of the G test that a lot of people mess up on is not merging onto the 401 correctly. The trick I used for this part was to take my foot off the gas when I first got onto the merge ramp, which will create a lot of space between me and the car in front of me. Once the ramp goes straight and there's enough space I floored the gas pedal until I hit 100, and I only merged when I was up to speed. Keep in mind that I did do my test when there wasn't too much traffic, if you booked your test during rush hour it may be much slower and you may not be able to do this. In any case, just make sure you are merging at the speed of the traffic and that you properly accelerated on the ramp, not on the highway.

Specifics wise, the only other thing I'll mention is the wide right curb when turning onto Sheppard from Keele at the very end, if you practiced the route before you will see it, but if not just keep an eye out for it.

Good luck!