The key to passing your test is practice and it doesn't involve any magick what so ever. Another tip that's easier said than done is to try and remain calm. If you psych yourself out worrying about it, tense up, etc...you can be distracted by your own worries. Just remember it's not the end of the world if you have to retake the test.
Maybe a good luck spell can help you pass. You should practice driving instead because that'll actually help. Practicing doesn't make you perfect, but it'll make you better. I just don't recommend that you cast a "better driver spell" because sometimes spells backfire and there can be many negative outcomes of the spell. I wish you luck on the test!