To also add fuel to the 'supercar' debate - the GTR is a sports car, not a supercar.
Sure it's fast and pretty darn swanky - but all GTRs (even the Mines R34) started their lives on a robotics equipped production line in Japan. The same sort of facility that makes Pulsars and Maximas. All Skylines (R's and T's) are mass-produced sports cars.
If they can be compared to anything European - it's German. BMWs, Benzes and Porsches are also mass-produced. To which end, I see all mass-market models from these and other marques as sports cars. Compare a stock R with a 4WD 911, or a GTSt with a Boxter - and you'll have yourself a better comparison.
$50k GTR vs. $500k McLaren? Please.
Have you ever been to the Ferrari factory? Seen how they hand-build a Lambo? Looked at the materials engineering behind the McLaren development? These cars share more in common with fighter aircraft and Formula 1 race cars than they do with their road-going bretheren. Yes - most of these cars utilise modern production techniques - but the amount of personal care received by even the most basic 355 is enough to set these cars apart.
Hell - look at the price tag!
There is no argument as to the sporting competency of a Skyline - R or T - and sure, stock for stock, an R is faster than many other cars out there. But - what the Skylines have up their sleeve is potential - this point being illustrated time and time again when we see modified examples exhibiting amazing behaviour. This potential is what makes the cars we drive great. It's what makes them envied and admired... but out of the box, the Skyline is just another well-engineered, showroom edition sportscar.
Performance bargain? Yes.
Massive potential? Yes.
World beating supercar? No.