Quote Originally Posted by netburner
Because the McLaren was driven at that speed by Martin Brundle at VW-Testtrack Ehra-Lessien in Germany, but nobody tested out the Koenigsegg by now. That is only a theoretical number. It's like the Ferrari Enzo, everybody said it would go about 350kph and then there was a big test at Nardo/Italy (against SLR, CGT, Murciélago etc) and it went 361kph.
Andy Wallace was driving the car that went into the record books at 386km/h, but actually went 391.

The thing about Guinness records is that they need to be independantly verifieyed/ measured.

The CCR could do 400mph, but if they don't fill in the requisite forms and get the proper time/ speed recordings then it won't be official, and it won't be in the book.