The car was parked at the back of the hospital, since the front was crowded with reporters trying to get the attention of the Russo family to make a statement, over the shame and disgrace Joanna, Diego's mother has brought to them.
During the ride to the hospital, it was only by the grace of God that Diego didn't piss on himself. He has never had a good relationship with the old man, and what his mother did complicated things for him.
It was a silent ride to the hospital, but he would glance at his grandfather from time to time, to see how hard it was for him to control himself, and not get rid of him just like his mother.
When the car stopped, Diego was scared because if there's anything he knew, it has to be the fact that they are going to meet his father, and his grandfather was going to tell him the truth about him.