Oddly enough, the ban has nothing at all to do with the Stuttgart-based automaker; instead, the ban comes from rival game designer EA Sports, who happens to own the rights to use Porsche vehicles in its own game franchise, the Need For Speed series.
Previous versions of Forza Motorsport included Porsche vehicles, but only because EA was willing to license them to Turn 10, the game designer behind the Forza series.
Originally, the Forza 4 game was to contain some 35 Porsches, but plans changed when EA decided against licensing the content to Turn 10 this time 'round. It seems that EA is doing all it can these days to protect the Need For Speed franchise, hence the reason for its decision.
That’s not to say that Forza Motorsport 4 will be entirely sans-Porsche; although stock Porsche vehicles won’t be in the game, EA doesn’t own the rights to tuned Porsche cars.
Germany's Ruf will have three of its Porsche-based creations in Forza Motorsport 4, while the other 31 missing Porsches will be replaced by models from other manufacturers when the game launches this October.