Heh, not really! I'm also an SSDC student, just passed TP two
days ago. Also had fixed instructor, fixed car. But on Mon during
my revision, my usual car sent for servicing, so they allocated me
car 55.
Then on my test, guess what, I got car 55! I was so happy, haha.
Cos on Mon I remember telling my instructor: "Wah, this 55, the
accelerator not very sensitive" and some other things, so I kinda
knew what to expect when driving it during my TP. 
Anyway, I also chose school over pte instructor cos scared the pte
instructor not dedicated enough (heard too many horror stories). My
fixed instructor in school was very, very good.