if its a test, then you can run what you like at a test.
The FIA have said originally that the cars are legal, but its happened before that race marshalls have declared cars illegal after the FIA have sai they were ok.
Pretty old news this, there has been discussions for a couple of months about this.
In short this is to do with difusers, which have a limit on size and height. In particular this year they must have a flat horizontal top and have a limited height.
Some teams have designed the rear crash structure or the like (which may be above and behind the diffuser) that just happen to be of a shape and form that aids the diffuser and effectivelly entends it.
To me it seems that technically they are legal, as strictly they follow the rules and this why the FIA have said they are legal as each component part are legal and the rear crash structure will have been declared legal as a crash structure. However, they are also clearly going against the intention or 'spirit 'of the rules and if the rear structure is declared to be acting as or part of the diffuser then they are illegal.
Red Bull are most outraged as they have gone a completely different route to all the other teams with the rear suspension and are the only team to use such a system. Which just happens to mean that if declared illegal they are the only team that would not be able to modify their design as the suspension system they are using wont allow it. (with out major major changes)
IMO it goes against the intention of the FIA to reduce downforce and so i think they will be declared illegal. However, i suspect it may be a compromise and that teams with this design will be allowed to run for the first 3 or 4 races with this system.
