I think a lot of it comes down to nerves & prep work... My first driving instructor felt like my best m8, and I think looking back that was a mistake - I was far too casual with him. The driving test instructor was also like hitler in a posh suit. Very carried away with his own importance. My second driving instructor wasa lot more serious while still being friendly. Also made sure he gave me every tip, and worked on my areas of weakness. The second test instructor was an older guy and was far more experienced. Before I even got in the car he simply said to me "I'm not here to fail you...just to make sure you obey the law". Put me at ease straight away! And I passed :P