Yup, those are prototypes designed by Adrian Newey exclusively for GT5. There's even a special challenge within the game in where you have to drive them and beat Sebastian Vettel's record. Of course, it's the hardest event in the entire game, even getting a bronze time is hard, given the unique characteristics of the car (over 1500 HP, extreme downforce, able to do one lap around Suzuka under 1.10).

Damn those are beast cars! 1500 HP is just ridiculous.

You bet. To demonstrate how insane they are, here's a couple of laps I did with them:

My gold time on the Sebastian Vettel Suzuka event
http://www.youtube.com/watch?v=3BpT-12EK68

My best time on Nurburgring 24H layout
http://www.youtube.com/watch?v=vX-J8GrYa8w

(don't know how to embed on the new gamerconnect, the HTML doesn't seem to update when I incorporate the video).

Ok WTF that doesn't seem even possible! That car can take tight corners at over 200 MPH, and can easily reach speeds of over 400?!?

Have they actually test driven this car IRL?

Or unless thats KPH which would make MUCH more sense (still would be insanity though)

it's not actually a real car. it's a prototype they made in game to demonstrate how far we could go with racing tech if we had no restrictions.

Ah ok I was gonna say.

It's KPH, and yeah, just like Bugrimmar said, it's a prototype designed by Adrian Newey for the game only. The major problem of such a car IRL is the G-forces, which can go all the way to 8 in some extreme cornering.
To be able to substain so many Gs, special racing suits must be designed (which would be more akin to fighter jet pilot suits) and new safety regulations should be in place in the tracks, in case of slips out of the track and even crashes between different X2010 cars.

Unfortunately, with the way that F1 (or pretty much any motorsport today) is evolving, we'll probably never see such a car.