Remember when Rubens beat Stig. TG can make up a story stig killed himself (in the new series) after that and a a lot of replacement "Stig's" were invited to the track to get the new job. Here TG can invite some odd 20 masked stig with all kinds masks (like batman, rainbow stig, yellow stig, the flash, spiderman etc) to lap the liana to beat Rubens. Finally, the Stig which beats rubens gets the job and there, with it an introduced new colour. I am not sure about the personality bit though. Having an unresponsive Stig was great. Best keep the same character style while just playing around with the colours.
I am still in favour of white. British racing green...does not cut it. Back to black, nah. Invisible/camoflage stig is good but then imagine the amount of wardrobe TG needs everytime the Stig comes out.