I have a 2012 sportback (62 plate 138 DTI sport) which has light clusters in the boot (including reverse!) as well as the main car body. I am planning to fit a parking sensor (meta targa) and since the reg plate is in the boot I hope it won't be too difficult a job. I have seen 'how to's' on how to remove the trim but I need to tap into the reverse light power supply. There are 4 wires going to this 'light': in order left to right looking towards the rear on passenger side: blue and red, brown, yellow and white, blue and red. I need to tap into the power supply and an earth. Any help on which is which would be much appreciated. Has anyone tried this sensor on an a3 - is it any good? I had it fitted to my previous car (vectra ) and it was excellent.