Tesla's Full Self-Driving (FSD) Beta data, as reported by a group of beta testers, shows a decline in performance, with miles driven per disengagement decreasing by 54% since March. This data is limited, but it suggests that the FSD Beta program may not be making progress. Tesla has not released official disengagement data, unlike other companies developing self-driving systems. The lack of transparency and the reported poor performance of FSD Beta have raised concerns among users and experts.