I don't see how they can allow some teams to use third cars, but not every team. The third car could easily be used as a mobile chicane to protect the other 2 team cars, even assuming that the third car is not eligible for points. If it IS eligible for points, it makes a complete mockery of the WCC by conferring a huge advantage upon the "chosen" teams. I would expect a fair number of lawsuits to be filed if third cars are instituted.