I just stumbled upon Diarium while looking for an alternative app for DayOne, to keep my data more private. But it should be able fit into my car automation.
currently:
If iPhone connects with CarPlay:
get current position (street/city and coordinates)
compose a text "Travel starts %currentTime% at %street%, %city% <newline> %LON% / %LAT%"
add new entry to the car log diary in DayOne with that text
And the same with "Travel stops" when connection to CarPlay is going offline.
And I'd really like to have this feature in Diarium, too.