He disabled autopilot right before the crash. Before crash - you can see autopilot is on with rainbow road visualization, then cuts into his reaction, then at crash it's disabled - https://youtu.be/IQJL3htsDyQ?t=942

Caveat: Autopilot is known to disable itself right before the crash (if it senses it) tho. I doubt this is the case because he would've obviously mentioned.