1. I (prefer) my tea very hot.
Here (I) is the subject, (my) is the direct object and (tea) is the indirect object. Therefore, the (prefer) verb displays a grammatical function since the semantic role changes in passive form.
2. She (has won) a brand new car.
Here (she) is the subject and (car) is the direct object. Therefore, (has won) verb displays a semantic function. The semantic role does not change in passive form.