turns out she was also in the crime game as a driver on a job that went sour and she was badly injured from the crash. So we have quite a lengthy dialogue on the way to her requested location and it turns out that if you get her there fast enough, she survives and becomes a wheelman that you can choose for heists later.
Tho she can also die if you don't get her there in time and would just keel over in your car (I did the part twice cuz she died the first time cuz I thought I could fukk around on my phone just down the street from her off-the-books doctor, not knowing that she'd actually die after a certain amount of time passed, as there's no timer or anything), so you wouldn't get access to her later.