Apparently, this ~is~ was a Gentlemen's agreement of the German automakers, to stop the competition for top-speed at 250km/h. Most adhered to it, except Porsche

Apparently, this ~is~ was a Gentlemen's agreement of the German automakers, to stop the competition for top-speed at 250km/h. Most adhered to it, except Porsche. But nowadays most offer you a special package which will remove the artificial limit, often for another 4-5 digit amount.