I have a relation between the model CarManager and PriceManager

in the pricemanager fields.yaml

car :
    span: left
    type: relation
    label: exitcontrol.carmanager::lang.modelpricedata.car

in my model for pricemanager:

 public $belongsTo = ['car' => ['\ExitControl\CarManager\Models\Manager','key' => 'car_id']]

How can I use the method getCarOptions($key) { }

To return fields formatted in such a way that the fields name and code and returned as "ECAR Economy Car blue" where the capitalised letters are the code, and the Economy Car blue is the name?

I can't find any example code where I can learn from how to set this up.

I know getCarOptions($key) is the key to doing this, but I have no idea how to get the values from the model and returning it in a way so it can be used.