OK, I've done a bit of digging.
SimBin (or 10tacle that owns it and Blimey! games) has a 10 year rights deal with the FIA for GT racing, it expires in 2012. (reference)
So, why not include all the official cars, tracks and teams? Well, rumour has it that Ferrari and Porsche are increasingly worried about their cars being represented 'damaged' in computer games. This was also a rumor in Test Drive Unlimited as well. So, I can only guess that if SimBin couldn't included all car because of limitations on the damage model then it's game over for an official game of any worthy note.
It gets worse though. It seems that from an official interview SimBin have implied that none of the cars in GTR-E have proven stats. Thats to say all the actual physic's on the individual cars behaviour are completely fiction. This seems to have been the case in Race 07 also. SimBin put a positive spin on this be saying that cars have been "modelled closely to each others statistics to give a closer racing experience".
So, imho, with the exception of the actual graphical model of the cars are no representation of the real life cars as Need for Speed or Test Drive Unlimited. And if I'm going to play a completely fictious driving game then I'll head back to TDU, ok the handling was a joke but at least the model where great and you could cruise the streets!
I think the serious racing community won't be taking this title to their sites. If the above is true that I think I'll hold off purchasing this one. I'll stick with GTR2, GTL and rFactor