Unstructed data field: Query all values from array of objects by key
Grab the elements from the json array with json_array_elements and reassemble them with json_agg:

select id, json_agg(cars) from (
  select 
    id,
    json_array_elements(data-&gt;'personalVehicle')-&gt;&gt;'model' as cars
  from t
) subq
group by id


Output:

1   ["Toyota", "Honda"]
3   ["Chevrolet", "Ford"]
2   ["Renault", "Citroën"]


Here's a fiddle.