Here is some further discussion about the 40% claim.
https://www.autoblog.com/2018/05/03/nhtsa-disputes-tesla-safety-claim-autopilot/
https://arstechnica.com/cars/2018/05/sorry-elon-musk-theres-no-clear-evidence-autopilot-saves-lives/
How would you explain the 40% drop in airbag deployment after the installation of autosteer?