In an email sent by Carsten Schumacher, CEO of Capircorn Nurburgring GmbH, to Carscoops, the official reason was stated thusly: "Following the tragic accident on 28 March 2015, the German motorsport association (DMSB) introduced speed limits for races at the Nürburgring. Capricorn Nurburgring GmbH has decided to extend these speed limits to other activities on the Nordschleife, which is why record drives are currently not permitted on the Nürburgring Nordschleife."
The crash referred to by Schumacher involved a factory-backed Nissan GT-R, during a VLN endurance race, killing an onlooker after flipping and flying into a spectator area.
These new restrictions for manufacturers were only recently discovered because Koenigsegg wanted to best the Porsche 918's 6:57 lap record with its One:1 hypercar. The record attempt was to be part of a documentary movie titled Apex.
On the documentary's blog, J.F. Musial, CEO of the company filming Apex, said that the Swedish company got as far as booking helicopters; these plans have now been placed on ice.
Autoblog believes that areas where cars are known to catch air, such as the Tiergarten, Flugplatz, Schwedenkreuz and Antoniusbuche, now have 200km/h speed limits in place. There's also 250km/h speed restriction along the Doettinger Hoehe straight.