Hey pierowmaniac,
Thanks for the reply and verifying that the car stereo firmware was up to date.
Question, do you find this refreshing happening when using Apple Maps while on a Wi-Fi connection, as opposed to a cellular connection, like when in the car?
This can isolate the issue to the network, as opposed to the iOS, so you can contact the correct place for help.
If Maps works as expected with Wi-Fi, but not in some cellular locations, contact your carrier. (It can be super helpful to provide location info)
if Maps refreshes also while using Wi-Fi, contact Apple Support: Get Support
Cheers!