No, at LeMans there doesn't have to be a road car, it depends on the class raced in, the 97 Nissan R390GT1 was as it's name suggests, in the GT-1 class which required at least one road car, then tin 1998 they entered again and had to make another road car so theres two a 97 and 98 model R390GT1 road car, the 98 GT-One was also in the GT-1 class and had to have a road version to enter, at the en of that season the rules changed and the 99 GT-One was then entered in the LMR class which classed it as a prototype so it didn't nead a road version. The old group C racers were also a prototype class aswas the group that replaced them which the 91 787B entered, so theres no road version of the 787B, Sauber C9 or Nissan R89CP ect.