Hi JP, welcome to the forum and becoming a Captiva owner. My first thought would be to enquire with your Chevrolet dealer for suitable sat nav. Better chance of a perfect fit.
I was slightly confused that you say you have a 2012 SX; I though SX was from the series I model where as 2012 series IImodel (2011-2012) would be a LS, LT or LTZ; or have Chevy changed model codes again!?
Aussie Ed.