Lecture over.

I think there are enough modern super cars in GT5. They are all getting very similar, and lack a particular character, unlike other cars usually older.
Allow me to disagree here! The achievements older supercars have managed are very impressive indeed , but of course that doesn't means that today's supercars don't manage to make their own impressive achievements.
First of all ,on topic, the Aventador has already managed ,to beat cars like Bugatti Veyron Supersport, Gumpert Apollo S, Ascari A10, Koenigsegg CCX and Nissan GTR on the Top Gear Test track . that alone is impressive, it shows that the Aventador, on it's first steps has already achieved something, and it has already proved it's value as a car.
For one example, what Ultima GTR has achieved is not impressive? A car built by a small company and costs only around 120.000 dollars managed to do better times on the Top Gear Test track than cars like Gumpert Apollo S, Bugatti veyron ( and Veyron Supersport), Ariel Atom V8, Mclaren MP4-12C, CCX, MC12, Enzo and many other cars. A tuned version of it managed to beat even the Ferrari FXX on that track!!
Second example the Gumpert Apollo Sport. That car has managed to do on the Nürburgring better times than cars like the GTR, ACR, ZR1, Porshe 911 GT2, MC12 and many others! And it has been made by a small company too.
Third example the SSC Ultimate Aero. With just a v8 twin-turbo engine , it managed to beat the world record of a Quad Turbocharged monster like the Veyron (that cost more than double of the price than the SSC costs). And just with that V8 it achieved 1183 bhp horsepower as oposed to 1001 bhp the Quad Turbocharged engine of the Veyron Achieves. And SSC hasn't even the support of Volkswagen (like Bugatti has ) ( Even Mclaren who had that record at the 90s had the support of BMW).
What I'm trying to say? What older supercars have managed, is of course impressive, but also is what many of today's supercars manage to achieve! Also many of them , come from small companies with small budgets , unlike large companies like Ferrari, Porsche, Honda, Nissan, something that makes their achievements even more impressive!
And of course they are not some "generic" "space-age" cars without a character.