Bugatti retires Chiron test mule after eight years and over 70,000km of running

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A matte surface, adhesive strips, scratches and minor grazes bear witness to the tough life Bugatti Chiron chassis 4-005 has led. For more than eight years, the vehicle served as an electronic and electrics development hack for the company, running across multiple continents and in all climatic conditions.

Test engineers tend to develop a prototype for a specific task then test their systems until shortly after the start of production, after which the vehicle is disposed of. But not so with the ‘Four Five’, as the car is referred to by Bugatti’s engineers (the four stands for ‘prototype’ and the five stands for the fifth prototype of the Chiron). One of eight prototypes created, 4-005 served predominantly as a software test and development platform for the Chiron’s 30 or so control units.

Rüdiger Warda, who has been developing Bugatti vehicles for almost 20 years and is responsible for the Chiron’s infotainment and audio system, remarked, “In the case of the 4-005, we performed all the tests and were on the road for many weeks, and this brings you together. The prototype shaped our work and with the prototype we shaped the Chiron.”

Before the Chiron was launched to market in 2016, the company’s development team traveled across the USA and Europe monitoring and fine-tuning the vehicle systems. Death Valley, the Grand Canyon, Granada or the Grossglockner – the maps and navigation system had to work impeccably in every country, as did the prototype’s satellite, aerial, radio and phone reception. For example, Bugatti’s engineers monitored factors such as how the telemetric data behaved when the car drove through different communication networks or was left without a network connection.

During heat tests in the desert, the air-conditioning system’s cooling flows, responsiveness and noise levels were monitored. “There are many areas that can be simulated, but the final tuning is done on the road over many weeks,” explained Warda. 4-005 was also used as a testbed for updates before they went into production. These included new navigation system functions and conference calling as well as HMI menu navigation concepts.

“Developing a combination of a pure driving machine and comfortable, intuitive operation was challenging. With Bugatti, driving is part of the experience – the menu navigation should only support it,” noted Warda. For example, with the map display, Bugatti selected a black background with blue symbols and white writing. When the speed key is activated, the infotainment system closes down completely. The driver doesn’t need any distractions when driving at 400km/h and is left to be able to concentrate fully on driving.

Engineer Mark Schröder has worked on the development of the Chiron’s human-machine interface (HMI) since 2011, including the menu navigation. “We want to provide the driver with a lot of information and present this information logically and elegantly. It also needs to be intuitive to operate,” he explained.

To achieve a timeless and elegant design, Bugatti opted for a centralized speed display with high-resolution, 6in displays alongside it. The four round control elements in the center console for the air-conditioning feature a second display level. “We determined during test drives that it was important for the front-seat passenger to receive vehicle information. We can present this information on the displays,” Schröder added. In addition, depending on the country configuration, the infotainment system can feature 30 menus within six main menus.

As well as functionality, Bugatti paid close attention to both the look and feel of contact. For example, all the controls are balanced and require the same torque as the controls on the steering wheel when being adjusted.

Schröder noted that when he had difficulty reading the menu navigation writing during a test drive in Arizona, USA, he came up with a solution right away. Much like the electronic paper display of an e-book reader, the display background now changes from black to white and the writing from white to black when signaled to do so by a sun sensor. “We discover many of the detail solutions during drives, discuss them within the team and then realize them, starting with the 4-005,” he said.

Tuning and adjustment of the sound system were also undertaken in 4-005. According to Bugatti, hi-fi experts spent days experimenting with different sounds and pieces of music to find the perfect balance, ultimately settling on a system using four tweeters with a 1-karat diamond membrane, two bass-midrange speakers and two subwoofers.

Even though it is a piece of work equipment, Bugatti’s engineers recall drives in the Chiron as always being special. “In spite of it being an immense feat, we drove for up to 10 hours at a time – and got out of the car feeling fit in the evenings,” remarked engineer Norbert Uffmann. Finally, after eight years and more than 74,000km, prototype 4-005 is heading into its well-earned retirement.

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Lawrence has been covering engineering subjects – with a focus on motorsport technology – since 2007 and has edited and contributed to a variety of international titles. Currently, he oversees Automotive Powertrain Technology International and Professional Motorsport World magazines as editor.

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