SS 300+ customers have an option to take their car/have a ride in the prototype for a 300 mph run at VAG's Ehra-Lessien track. Regular Super Sport owners don't get that option.
Thirty well-heeled customers set to own near-identical cars to 490km/h record-setter, but limited to 440km/h
www.carsales.com.au
13 Sep 2019
"Bugatti spokesman Tim Bravo told carsales.com.au at the Frankfurt motor show."
Further~
"As already reported, the Super Sport 300+ will be speed limited to 440km/h,
but there’s NO truth to reports by some media that
customers can have the speed-limiter deactivated and attempt to replicate former Le Mans winner Andy Wallace’s recent record-setting feat at Ehra-Lessien.
“If you’ve ever driven above 400km/h, you’d know that is already very fast,” says Bravo. “The speed-limiter won’t be deactivated for safety reasons. To go beyond that, conditions have to be perfect and a professional driver is needed.”
“For the record, we had a whole team of engineers optimising every parameter and we X-rayed all the tyres, and yet Andy still had to be very careful because of the winds at Ehra-Lessien that kept changing. Every movement at that speed is multiplied.”
Tim Bravo was the Head of Communications for Bugatti. Now at Lamborghini.
Ehra-Lessien is owned by Volkswagen and for the same reasons they didn't go and do a two way average no clients will ever be allowed to do anywhere near 300MPH.
~Insurance I was told because an engineer lost his life there in testing but that's from memory. Audi I think not sure.
I also saw the Triple F Collection who own a Bugatti Chiron Supersport confirm both variants are electronically limited.
I have to go with the above, for now and I've scoured for information for years.