First thing the title tells us? It's not Daisy Werthan—it's Miss Daisy. Right off the bat, we know that she's a fancy southern lady who's got to be addressed properly by her servants.
She's definitely Miss Daisy to her driver, whom the title tells us is the other big part of the story. Miss Daisy's greatest struggle is slowly relinquishing control of her life and letting someone else drive her, whether literally (Hoke behind the wheel) or figuratively (taking care of her).
Hoke becomes a "driving" force in Miss Daisy's life, that's for sure.