Experts testify BMW reached up to 329 km/h before fatal A1 crash in Poland

Expert findings on vehicle speeds

During a hearing on 21 September 2026 at the District Court in Piotrków Trybunalski, accident reconstruction experts submitted a supplementary report spanning nearly 400 pages in the trial of Sebastian M. The defendant stands accused of causing a fatal collision on the A1 motorway on 16 September 2023 that killed three people. The expert team determined that the defendant operated his BMW M850i xDrive at speeds between 315 and 329 km/h in the moments preceding the collision. Investigators calculated that the BMW collided with the victim vehicle at a speed between 253 and 268 km/h, while the victim car, a Kia, moved at approximately 140 km/h with its cruise control engaged. Data recovered during the investigation from the BMW Bosch LRR4/LRR5 long-range radar registered a speed reading of 300.6 km/h at the exact moment the device was destroyed.

“Our opinions indicate unequivocally that the speed of the BMW vehicle was in the range of 315-329 km/h. In this range, the driver operated his vehicle. Meanwhile, the Kia was traveling at around 140 km/h with cruise control engaged.”

Kia cruise control speed140

BMW impact speed (lower bound)253

BMW impact speed (upper bound)268

BMW radar reading at destruction300.6

BMW prior speed (lower bound)315

BMW prior speed (upper bound)329

Kia cruise control speed

140 km/h

BMW impact speed (lower bound)

253 km/h

BMW impact speed (upper bound)

268 km/h

BMW radar reading at destruction

300.6 km/h

BMW prior speed (lower bound)

315 km/h

BMW prior speed (upper bound)

329 km/h

Data from the article text

Collision dynamics and defense refutations

The court heard that the BMW struck the rear left corner of the Kia with its front right section. Expert analysis of vehicle deformities, road marks, onboard digital event data recorders, and dashcam recordings demonstrated that the Kia maintained a constant path in the center lane without swerving. Forensic examiners stated that the collision occurred when the BMW initiated a lane change from the left lane into the middle lane. Additionally, technical inspections revealed that the BMW had been modified through tuning, which voided its regulatory approval for use on public roads. Reconstruction specialists also challenged a private technical assessment submitted by the defense, identifying fundamental measurement errors in axle track width, braking skid lengths, and map scaling.

“I have been dealing with road accidents for 25 years. In my career, I have not encountered such speeds on the road as those we are dealing with in this analyzed accident.”

Investigation history and procedural steps

The crash took place near the village of Sierosław near Piotrków Trybunalski, causing the Kia to strike roadside barriers and catch fire. The collision resulted in the deaths of a married couple from Myszków, Patryk and Martyna, alongside their four-year-old son Oliwier. Following the incident, Sebastian M. left Poland and traveled through Germany and Turkey before reaching the United Arab Emirates. Emirati authorities detained him, leading to his extradition to Poland in May 2025. The trial formally commenced in October 2025 and has generated nearly 30 volumes of case files. The 21 September session concluded the witness and expert witness testimony phase, with assistant prosecutor representative Katarzyna Hebda submitting dozens of formal inquiries. Closing arguments from both legal teams are scheduled for October 2026, with the defendant facing a maximum statutory penalty of up to 8 years in prison.