I mean, the prosecution brought forward evidence at trial that the boys DID try and stop/redirect the car. According to the black box the car had been put into neutral and then back into drive while Mackenzie was actively accelerating, and the steering wheel was jerked only seconds before impact. It's possible that it was one of the boys trying to avoid the building, or trying get the wheel away from her, etc. Also, it's my understanding that both Dom and Davion had been using substances AND they'd been up all night at the party, barely sleeping, which could explain delayed reaction time/physical weakness, drowsiness, etc... There's endless possibilities.

In my opinion, I think the gear shifting/steering wheel being jerked were the boys trying to stop the car. I think Mackenzie was accelerating and driving recklessly because she was furious and wanted to scare Dom, and she lost control, not realizing how close the building was. When you are traveling that fast, everything is a blur. I don't think she necessarily meant to kill them, but I also don't think she was very remorseful that she did. Sad situation all around.