I'm not seeing where the X2010 is overrated. "Overrated" would suggest that people make it out to be better than it is. That isn't possible. The X2010 simply blows every other car out of the water, no matter where you take it. There's no track on which the FGT, Veyron, F2007, F10, et cetera ever beat the X2010. If it's every bit as godly as they say, it's not overrated but properly rated. Not personally liking it or hating to see so many people fawn over it doesn't make it overrated.
Like anybody that knows anything about cars and racing, I'm definitely going with the Veyron as the most overrated. As has probably been illustrated in replies that I never bothered to read, the car looks fantastic on paper but isn't worth a bucket of monkey crap in most races and can generally be beaten by several other high-end cars. There isn't even very many places on Earth where it can reach its top speed, but no shortage of places where its terrible cornering comes into play.