The door lines are a separate texture on 1 side of the car, then the back half uses a big texture that makes the bodylines from the rear half of the car. The way it was also modeled wouldn't be able to do it.
I detach doors all the time (All of icekid's cars, Shift cars etc) if they have 3D bodylines, I personally do not like flat bodylines, though with this car and its quality I made it a exception. I do small/medium parts of modeling like the Cinque I did with the engine cover and rear diffuser, side vents on the fenders, not a whole car and updating part by part with 3D bodylines I will admit that. The way this LP670 was made just wouldn't work for what it has.
This was also a exclusive to GTR2 that was recently released I do not wanna just jump in and edit everything they they have been working on for a very long time. I only edit the main parts that TDU needs in order to work.
I've been waiting for this car since 17 November 09 and got it/permission on the 21 March 2010. Imo its not necessary to have opening doors all the time. My opinion, you drive not opening doors. ;)