Engineers from Dallara pitched in on chassis and aero stability. But it's always been the tires that have held Bugatti back; even though Michelin tested its shoes up to 300 mph in preparation for Koenigsegg's top speed run two years ago, Bugatti's longtime supplier went through an obsessive quest to produce the perfect rubber here. That included X-raying potential tires to search for the smallest deficiencies that might rear their heads at speed and pushing candidates to 317 mph in bench tests. Every system on the car was shaken down as much as humanly possible in the laboratory before Bugatti gunned it on August 2.

The result: some truly mind-melting numbers from the record run. At 300 mph, the Bugatti Chiron is covering a mile every 12 seconds. That's 446 feet a second. The tires are rotating at 4,100 times per minute. What we don't know yet is how long the Chiron can keep up that pace; for comparison, the Veyron would drain its entire 26-gallon fuel tank in 12 minutes running at full clip, and its tires weren't rated for more than 15 minutes above 250 mph.

So Bugatti's done it. The quest for 300 mph is officially over—and with it, the focus on top speed that's defined the automaker for a decade-plus. Though this will undoubtedly prompt Koenigsegg or Hennessey or someone else to push for 305 mph, Bugatti says that this run will be its final statement on the matter. It's officially done with the speed record game.

"Our goal was to be the first manufacturer ever to reach the magic 300-mile-per-hour mark. We have now achieved this – making ourselves, the entire team and myself, incredibly proud." Bugatti president Stephan Winkelmann said. "We have shown several times that we build the fastest cars in the world. In future we will focus on other areas."