"All it needs is for the phone to record throttle use for 2-3 laps and just play back that pattern?" It's really not that simple, unfortunately. It doesn't know where the cars are (other than when they pass the lap counter), so wouldn't know when to slow down/speed up. You can't rely on timing, cos a given throttle setting won't always have the car running at the same speed. A variance of just 1% (and it's way higher than that in practice, ISTM) gets you a few seconds out after a bunch of laps, so it becomes useless. Even if the throttle settings gave you a 100% accurate predictable speed, the pace car could be slowed by another car in the same lane getting in the way.