Driving test in own car

Hi my driving test is in 2 weeks and my instructor recently got a new car which is a sporty fiesta, I can drive the car find but the back window and back side windows are so small everytime I've attempted a parallel park or left reverse I can't see properly at all and it would make me fail my test. Ive been insured on my own car since June so I'm confident in the car but I was just wondering if there's any didlsadvantage to sitting it in your own car? Are examiners more strict ? My friend did it in her own car and failed twice...

I failed my first test in my instructor's car mid July the day before I moved to a different city. Needless to say I felt pretty shi**y. When I moved I thought about getting a new instructor to help with new local routes etc, but my other half had just recently got a new car. I just decided to get insured on that (MUCH cheaper than paying for an instructor until my test date!) and went driving loads. I practised the manoeuvres loads as my instructor had given me reference points for his car which were no good in the new car! I sat the test about 5 weeks later and passed with only 2 minors. I felt absolutely no disadvantage at all. If you're comfortable and confident in your own car, then go for it. Just make sure it's of a test standard and you have a second interior mirror for the examiner.