It would be nice to use PHQL to get a model and a related models pre-hydrated in the model (like in Doctrine Fetch Joins https://docs.doctrine-project.org/en/2.1/reference/dql-doctrine-query-language.html#joins)
At the moment with PHQL it is possible to do
SELECT user.*, cars.* FROM UserModel user JOIN CarModel cars ON user.id = cars.userId WHERE user.id = 1
This would return a Complex ResultSet with Rows containing UserModel and CarModel. It would be better to return only a UserModel and access the cars like user->cars