Text size Roped off on the Volkswagen Group stand at the IAA Mobility auto show in Germany was perhaps the sexiest car present, the Porsche Mission X concept. The supercar is aimed at being the fastest road-legal vehicle at the Nürburgring race track’s Nordschleife loop. The inspiration, on Porsche’s 75th anniversary, was the legendary 1985 959, the fastest series-production car of its time, capable of traveling 196 miles per hour. A more modern ancestor was the 918 Spyder of 2013. Of late, Porsche, Rimac, and Tesla have been battling back and forth over the electric record at the German track….