Whoopsy:

Long tracks are not a problem for the 918, it's tracks with exceptionally long straights, lots of those, and not a lot of corners, that are the problem.  But outside of the Nardo test ring, I don't really see another track the 918 will have a problem with. 

Advantage of the 918 is that it can put a lot of distance between it and whatever on corner exits even if the other car can match the cornering speed, the other cars will always be playing catch up on straights, the straights need to be long enough for the other cars to catch and them pass, even catching the 918 is not enough, the strong brakes will mean it will brake later and regains the lead. 

Who would design such a track anyway (except tracks used for a specific (research) purpose), the corners are where the differences are made from a driver capability standpoint.