It depends on the age of your kid I believe. I have friends who are allowing their sons to watch Sophia and other girly cartoons. Because for them it helps the kids to understand gender equality when they grow up and not to discriminate other people when they grow up. It somehow true, when I was young I remember playing dolls with my cousins and it taught me to respect all people regardless of the gender.
I believe you should allow her to play with whatever interests her. :) Teach her at an early age not to limit herself. This will encourage her to form her own personality and it will inspire her to be whatever she wants to be. Plus: supporting her interests will make her feel how much you love her! :)
Definitely allow her to play with cars, too. My daughter has toy cars and enjoys car racing with her dad and baby brother. If your daughter is disinterested with dolls, give her time. Reintroduce a few days later.
You should encourage her to play with whatever interests her because play is genderless. Even role-playing is good for a children to discover themselves and learn about/empathize with other people.