On the A40 highway at night, French gendarmes logged an astonishing reading: 312 km/h (about 194 mph) on a stretch limited to 130 km/h (about 81 mph). In the Arve valley, in Haute-Savoie, a Porsche 911 GT3 was clocked at this incredible speed. The rapid-response team and the Bonneville motorized brigade were on site. They intercepted the car during the night of September 26–27. In a rare moment, they even captured the measurement on the display of their laser speed gun.
To gauge the scale of this record-breaking speeding, the Haute-Savoie gendarmerie posted the key figure. “182 km/h: this isn’t the speed at which this motorist was stopped. It’s the speeding excess observed.” This message appeared on the Haute-Savoie gendarmerie’s Facebook page. After applying the 5% technical margin used in France, the speed used for the case drops to 300 km/h (about 186 mph). The recorded excess speed is therefore 170 km/h (about 105 mph) over the 130 km/h limit. How did we get here, and what penalties now await this foreign driver behind the wheel of a GT3?
Record speed of 312 km/h on the A40
The events unfolded on the segment of the A40 that cuts through the Arve Valley. Known as the “white highway,” this road links Mâcon to Passy, passing through the Geneva region and providing access to the Mont-Blanc tunnel. On the night of September 26–27, law enforcement conducted a speed check with the Quick Intervention Team alongside the Bonneville motorized brigade. It was there that a Porsche 911 GT3, driven by a foreign national, was flashed at 312 km/h. That speed far outstrips what a production car can achieve. The 991-generation 911 GT3 is listed by the manufacturer at roughly 475–500 horsepower, with a top speed between 315 and 318 km/h (about 196–198 mph). According to the gendarmes, it represents the largest speeding excess ever recorded on a public road in France. The previous record earlier came from the same A40, where an Audi RS3 was clocked at 287 km/h in May.
Faced with such a number, Haute-Savoie officers did not hide their astonishment. “This is a first for Haute-Savoie. We’ve had speeds of 230 km/h, 290 km/h before, but never something like this. At 312 km/h, the radar does not lie,” said Captain Joël Contal of the Haute-Savoie gendarmerie in an interview with France 3 Auvergne-Rhône-Alpes. “Weekends come and go… and some irresponsible behaviors too. At 312 km/h, the driver covered almost 87 meters every second among other road users. Recklessness? Thrill-seeking? Either way, the consequences are real.” For comparison, at 130 km/h a vehicle covers about 36 meters each second—nearly 50 meters less per second than a Porsche already blasting along at 312 km/h.
What penalties could the Porsche 911 GT3 driver face after being clocked at 312 km/h
After the stop, the procedure for the driver was swift. “The driver, foreign national, had his vehicle placed under administrative seizure and his license retained on the spot. Before leaving the scene, he also had to lodge a security deposit of 1,500 euros, pending his judgment,” the Haute-Savoie gendarmerie explained. That deposit is money left with the authorities to cover potential court costs while awaiting the court’s decision. As things stand, the driver faces the penalties associated with a major speeding offense—more than 50 km/h over the limit. It is a misdemeanor punishable by up to three months in prison and fines up to 3,750 euros. The law also provides for license suspension, and possibly permanent confiscation of the vehicle.
These numbers gain real weight when you consider what 312 km/h means on the road. At that speed, a Porsche is traversing about 87 meters each second, versus roughly 36 meters per second at 130 km/h. In just one second, the gap is already more than 50 meters—the length of several cars lined up. According to France’s National Interministerial Observatory for Road Safety, speeding by more than 50 km/h remains a rarity, accounting for around 0.3% of all offenses recorded by authorities. Yet excessive speed continues to be a major factor in road fatalities. The A40 is a mountain corridor that carries substantial traffic between France, Switzerland, and Italy. It remains to be seen what sanction the court will choose for this driver and the 911 GT3, now out of service on the road.
