I am sorry but the new MagEZ Car Mount Pro is not compatible with the MagEZ Case for iPhone XS.
Because the MagEZ Car Mount Pro is the MagEZ® 2.0, while the MagEZ Case for iPhone XS is MagEZ® 1.0.
The New MagEZ Car Mount Pro supports the MagSafe® cases.
However, the MagEZ Case for iPhone XS is not a MagSafe® case, so they can not be magnetically attached together.
But the MagEZ Case for iPhone XS does compatible with the MagEZ Mount Qi, please check it here https://www.ipitaka.com/products/magez-mount-qi
We put special design metal plates inside of the MagEZ Case that avoids the position of the wireless charging area so that it can work with our built-in magnets MagEZ Mount Qi.
Also, you may wanna learn more details between the old MagEZ Mount (Qi) and the new MagEZ Car Mount Pro here https://www.ipitaka.com/collections/magez-system
I hope this helps. ;-)