hmm, i really think that its going to be hard to get the doors on that without mucking up the model. try some tut's and stuff to get used to how to model cars using the blueprints.
here's two of the best tut's...
http://www.lwg3d.com/forums/forumdisplay.php?f=242
Lewis's, using the spline patching technique, and my tut using the point extrusion technique.
Cheers,
Will