The xx4 is a very good car, but it also helps that so many people driving them, you are going to get a good percentage in any final as there are so many of them about. I have one Slim4 in the nationals compared with say around 60-70 XX4's.
And it is hard to get top drivers to run other cars, trust me
I agree with Stefke that the XX4 is beatable, and i will try my hardest to produce a car that will match and improve on the performance of the xx4