Firstly, look at the height of the fron wing, it is not 2005-spec, it is 2004. Not sure what year that McLaren is, but look at the height of the wing on both cars, and you will see that the endplates are actually a little lower than the McLarens, as well as the height of the front wing main-plane. Despite all of the side shots showing the F1 car has a higher nose, that front-on picture shows that it is not 2005-spec, but 2004.
People need to keep in mind that the shape of the wing itself can sometimes make it appear higher than it actually is (this is very apparent with the Sauber C24 and Toyota TF105 this year).
Now to get to your question about the width of the F1 car in GT4. It appears as though they are using the old pre-1998 specifications for width, and that the car has a track of 200 cm, instead of the current 150 cm (I believe).