@nicola1970 - The BMW's were given a huge amount of waivers. Basically their car is completely out of the "spirit" of the GT rules. The engine has been pulled back from its original position (towards the center). There are many other waivers.

 

It's almost as if the 3 series is such an un-competitive GT, they give it a whole bunch of race car style "waivers", making just as competitive, but more sporty than the competitors. Another one of these waivers is that they have larger restrictors than the other cars. Just watch how effortlessly they pass the 458s on the straight.

And thanks for that shot Spyderman. I never knew that about the engine, and they really moved that back quite a bit!