Today's top model Aston Martins and Porsches, as well as base model Ferraris and Lamborghinis are as fast or faster than the supercars of yesteryear. A Gallardo LP560-4 will absolutely dust a Lamborghini Countach, let alone a Miura. A 458 will smoke a Testarossa.
This performance advantage has led many so-called "experts" in the car field, as well as casual car enthusiasts from Montana to Mumbai to title these modern midengined sports cars "supercars." We've done it, too.
There is something that a Countach or a Testarossa has that a Gallardo or a 458 of today never will: super-ness.
Outright, quantifiable speed is only a small part of the supercar equation. Supercars are all about being absurd, impractical, and extreme. True supercars are so much more than regular family haulers that they don't even seem like cars anymore. A late model Countach, with all of its wings and wheel arches and scissor doors and whatever just looked and felt so different from a standard Chevrolet Celebrity that it could only be considered super.
Contrast that to the new Lexus LFA, a car that is often mistitled a "supercar." The Lexus is very fast. The Lexus looks good. But it is not so fast or so good looking that when you see one go by you shit yourself. When a Countach passes me on the highway at 160 miles an hour, yes I shit myself.
Mostly because that Countach is about to crash because a Countach is impossible to drive. The LFA is certainly faster than the old Lambo, but the Lexus is significantly less 'super.'
The same could be said for the Porsche 911 Turbo, the new Aston Martin Vanquish, and even the McLaren 12C. Those cars do not convey a sense that the driver of the car will, in the next five minutes: pop some designer drug you haven't even heard of, suffer an unexpected mechanical malfunction which will cost more than your house, and then crash into a schoolbus full of child orphan nuns. The Porsche, Aston, and McLaren are just too orderly, reliable, and user-friendly to convey that sense of theater.
This brings us to the Ferrari 458. "How could that not be a supercar," you ask. "It's got the right badge, it's crazy fast, the engine is in the middle, and it can do this:"
There is a reason why the Ferrari 458 is not a supercar and it is the same reason why the Ferrari 348 was not a supercar. There is a bigger, faster Ferrari in the range. The 348 stood in the shadow of the Testarossa just as the 458 stands in the shadow of the LaFerrari, even in the years before the LaFerrari debuted. You see, to be super you have to be way, way more extreme than anything else, and knowing that a car has a wilder big brother means the little car can never really be super.
This brings me to the true supercars of today: they are called hypercars. The McLaren P1, the LaFerrari, the old F60 Enzo, the Pagani, the Koenigsegg, the Aventador, and any other big dog twelve cylinder Lambos waiting in garages with five-digit repair bills. They are called hypercars only because people have overused the word supercars on things like the Audi R8, which is just a fast daily driver sports/GT car that Iron Man likes.
In summary: cars that don't make you think you'll get syphilis just by looking at them are not supercars. Cars that make you think they're going to explode because you touched the oil cap are supercars. I hope that clears things up.