Expert witness: EDR shows Tesla at 88 mph five seconds before crash; judge allows expert testimony over defense objections

A sergeant with the San Antonio Police Department testified at trial that event data from a 2021 Tesla Model 3 recorded the vehicle traveling 88 miles per hour five seconds before a crash and slowing to 33 miles per hour at the moment the airbag-control module recorded the event. Sergeant Davis said the EDR/ACM data, recorded at 0.2-second intervals, also showed braking recorded from five seconds out through impact and a near full-lock left steering input beginning about two seconds before the crash.

The testimony came after a courtroom exchange over whether Davis should be qualified as an expert. Defense attorney David McLean objected, arguing Davis had not had continuing education since initial training completed around 2018 and that vehicle electronics and downloads (notably for newer vehicles such as Teslas) had evolved. The judge overruled the defense on that point and ruled that “the witness will be allowed to testify in those areas as an expert,” permitting testimony on EDR extraction and analysis and on accident reconstruction.

Davis described his training and experience: academy crash-investigation basics, intermediate and advanced crash investigation, crash reconstruction, crush analysis, and both CDR retrieval and CDR analysis courses. He said he last performed an extraction in 2023 and that course offerings can be infrequent; he also said some updates are delivered by manufacturers and that retrieval software/hardware can change over time.

On the specific crash, Davis testified that the EDR recorded a steady deceleration from 88 mph at five seconds before the event to 74 mph at four seconds, 60 mph at three seconds, 50 mph at two seconds, 37 mph at one second and 33 mph at the time of the event. He said the braking indicator in the data registers that brakes were being applied through the interval but does not record braking force percentage. Davis also testified that the steering-wheel position changed from a small left input to roughly negative 357 degrees at the event (negative indicating left), reflecting a hard left steering maneuver beginning about two seconds before impact. He explained that a negative 357 denotes a near full-lock left turn.

Davis noted an anomaly in the odometer readings between two recorded events and said that ignition-cycle differences can occur for reasons such as tow-truck or impound activity; he testified that a single ignition-cycle anomaly does not necessarily invalidate the remainder of locked event data. He also recorded a maximum delta-v longitudinal of negative 50 kilometers per hour (about 31.06 mph), which he described as a moderate delta-v for vehicle-to-vehicle collisions and potentially severe for a pedestrian depending on circumstances.

Defense counsel repeatedly raised relevance and currency objections during cross-examination, contending the landscape of electric vehicles and manufacturer-provided data has changed since Davis’s initial training; the court sustained some objections but permitted the state to proceed on detailed EDR and reconstruction topics. The prosecution introduced state exhibits and video that Davis said matched the EDR timestamps for steering input and the timing of the event.

The court returned the jury to continue testimony after the evidentiary rulings; the direct examination concluded with the state confirming the EDR speeds and the witness saying speed and steering input were factors in the crash. The trial record shows objections, a short sidebar/parties-approach discussion, and the judge’s explicit allowance for Davis to testify as an expert in extraction/analysis and accident reconstruction.