From Wiki...
"A supercar is a very expensive and fast sports car. Supercars are marketed by automakers as unusual and include limited production specials from an "elite" automaker, standard-looking cars modified for power and performance, as well as models that appeal to enthusiasts from smaller manufacturers"
and "During the late 20th century, the term supercar was used to describe "a very expensive, fast or powerful car with a centrally located engine", and stated in more general terms: "it must be very fast, with sporting handling to match", "it should be sleek and eye-catching" and its price should be "one in a rarefied atmosphere of its own"
and from this source which goes on to discuss exotics in great detail...
http://www.examiner.com/article/exotic-cars-101-what-is-an-exotic-car-by-definition
"Applied as a term used to both describe and classify cars (as in "exotic cars"), the stipulative definition has been used to describe vehicles that are so rare and unusual, it's not likely the mass population will ever see one in person . 99% of the public will seldom be fortunate enough to get near one as a driver or passenger. Furthermore, chances are the average layperson won't even know what the cars are (by brand or feature definitions and specs) if they do happen to see one at a car show or on the road."
The Viper is a text book example of a supercar, and the ACRs and the T/A are also text book exotics...it doesn't get any clearer than that.
Bruce