If the 13 yo was the passenger, she's the one that put the car in gear.
As Anwar was trying to force his way back into the Honda by climbing on top of the girl in the driver’s seat, Leo said, the 13-year-old reached across from the passenger seat, turned on the ignition and “manipulated” the gear shift. The vehicle lurched forward and accelerated down the block before crashing, Leo said.
If the 13 yo was the passenger, she's the one that put the car in gear.
Sure sounds like she was very actively involved, though I'm not sure how this information could have been reliably obtained.
It's from the Washington Post, so they probably just made it up.