The Bugatti Chiron debuted back in 2016, but by then, Chiron 4-005 had already toured the world. It's one of eight prototype Chirons built by Bugatti, designed to shake out all the bugs and fine-tune what would become one of the quickest, fastest, and most exotic cars in the world.

Usually, we associate prototypes with pre-production development, but this one kept right on going once the veil was lifted. Chiron 4-005 (4 meaning prototype and 005 being its chronological number) was built primarily to handle software development, and that can range from infotainment systems to powertrain functions, right down to the welcome message that greets driver and passenger upon entry.

Gallery: Bugatti Chiron 4-005 Prototype

To that end, four-five was actually the very first Chiron to scour roads in the United States. It also turned high-speed laps at Nardo, suffered heat tests in South Africa, endured snow in Scandanavia, and its dull black finish bears scars from these endeavours. Whereas many Chirons may never exceed 1,000 miles in their everlasting life, this one's turned almost 50,000. It even felt the effects of an afterburner from a Eurofighter Typhoon, and while we're dying to hear the story, Bugatti doesn't elaborate further on that adventure.

What we do get, however, is a better understanding of the vehicle development process because it doesn't stop once production cars are on the road. In the case of four-five, various software updates or system changes to production cars still required testing and validation. After all, navigation maps around the world need testing in actual locations, and sound system upgrades might sound different in the mountains versus sea level. The only way to properly dial in such things is to hit the road, and through it all, Bugatti says its drivers and engineers always got out of the Chiron feeling refreshed.

Now, 4-005 is finally leaving service as a prototype vehicle. What exactly does that mean? Ordinarily, automakers crush prototypes as they could become a legal nightmare should they ever make their way into public hands. Of course, Bugatti isn't a typical manufacturer, and the Chiron certainly isn't a typical car, but four-five's fate is still a mystery. Bugatti simply says the car is "going into its well-earned retirement" so hopefully that means we'll see it again someday.