This is yet another example of the failings of capitalism; immature men with insecurity complexes will always demand fast cars to make up for their many physical and scial failings… and if they are demanded then they will be built.
But where is it in the interests of society to allow cars on the road that can do double or triple the legal speed limit? Just what is the point?
Maybe there is an argument for increasing the speed limit on motorways to 80 mph; maybe we should allow cars to go slightly faster than that to allow for overtaking… but why the hell should anyone be allowed to drice a car that goes faster than 85 miles per hour?
And YES this is state intervention!! – because I simply do not trust the competence of these drivers! There is no need for such powerful cars to be allowed!
And of course, the side issue of greater fuel efficiency is just an added bonus!