Apple CarPlay is known amongst its users as being temperamental at times, more so during its early periods, however as each iOS update rolls by, Apple CarPlay stability has improved in leaps and bounds.
Some CarPlay users do still experience disconnections with certain Apple CarPlay systems, be it factory fitted Apple CarPlay systems or Apple CarPlay Aftermarket head units.

A new iOS 12.1.3 update has released last night which is said to specifically resolve disconnections with certain Apple CarPlay systems whilst using it with Apple’s latest iPhones, including: iPhone XR, iPhone XS and iPhone XS Max.
Don’t expect much more improvements with Apple CarPlay in this minor update from Apple. We have to wait until June before we hear anything in regards to the CarPlay UI refresh, which is rumoured to be included with their upcoming iOS 13 update that’s due to release at the end of the year.