Initial media reports stated that Diana's car had collided with the pillar at 190 km/h (120 mph), and that the speedometer's needle had jammed at that position. It was later announced that the car's speed upon collision was 95–110 km/h (59–68 mph), about twice as fast as the speed limit of 50 km/h (31 mph).

On August 31, 1997, the Mercedes-Benz S280 carrying Princess Diana crashed into a pillar in the Pont de l'Alma tunnel in Paris. Official French and British investigations, including Operation Paget, estimated the car's speed at the moment of impact to be between 105 km/h and 110 km/h (approximately 65 to 68 mph). This was more than double the tunnel's posted speed limit of 50 km/h. Earlier reports of speeds reaching 190 km/h were debunked after technical analysis showed the speedometer was damaged and frozen, rather than reflecting the real-time velocity. The investigations concluded that the combination of high speed, the driver Henri Paul’s impairment from alcohol and prescription drugs, and the pressure from chasing paparazzi made the vehicle unrecoverable when it clipped a white Fiat Uno before striking the thirteenth pillar. Neither Diana nor the other passengers, except for bodyguard Trevor Rees-Jones, were wearing seatbelts.