get laravel join table name

how to get eloquent query join relation table name

$q = logistic_car::join('logistic_car_type', 'logistic_car_type_logistic_car_id', '=', 'logistic_car_id');

with $q->getModel()->getTable(); i can get main class table name, how can i get the "logistic_car_type" table name from eloquent query builder object ?

NB! i need to get from query builder, not from predefined variable and not from relationship