> we registered one accident for every 4.19 million miles driven in which drivers had Autopilot engaged [...] for those driving without Autopilot but with our active safety features, we registered one accident for every 2.05 million miles driven
This still isn't the correct comparison. Major selection bias with comparing miles with autopilot engaged to miles without it engaged, since autopilot cannot be engaged in all situations.
A better test would be to compare accidents in Tesla vehicles with the autopilot feature enabled (engaged or not) to accidents in Tesla vehicles with the autopilot feature disabled.
This still isn't the correct comparison. Major selection bias with comparing miles with autopilot engaged to miles without it engaged, since autopilot cannot be engaged in all situations.
A better test would be to compare accidents in Tesla vehicles with the autopilot feature enabled (engaged or not) to accidents in Tesla vehicles with the autopilot feature disabled.