There aint nothing wrong with Zev. He over played his dumb act and lost the passports. This time he tightened his shot group so to speak and is still pretending to be mentally handicapped, but not overplaying it to the point where he will do something dumb this time.
Wow, I think you are giving Zev way too much credit here.

I don't think he, or anyone else, has claimed that he is so mentally handicapped that it affects his intelligence. They have said that he has Asperger's, which affects his social skills and makes him a little awkward around people, lacking some tact perhaps. In fact they have barely even mentioned it this season, only once that I can remember (in one of the first episodes). So I don't think that Zev is playing dumb at all. He seems like an intelligent person who sometimes says things when he should keep his mouth shut instead (like when he complains about stuff). So I agree that there ain't nothing wrong with Zev, and I think that he and his partner would agree. Besides some awkward comments, he doesn't act any more or less dumb than the other racers.