Some things I notice...
The tyres are in terrible condition, that will make the car turn very unpredictably. You need new tyres without any chunks in them, front or rear.
The sensor lead will be jammed against the body, and that will give unpredictable handling as it will not allow the chassis to move correctly. When the body is on the car, nothing should be touching it except the body clips holding it up. All wires must be below the body on the inside, the body must float on the four posts, and the top body clips must not push down on the body. They need to be close, but not to push on the body.
Please don't take this the wrong way, but if you think this is a good 12th build, then you may have built problems in elsewhere. Is there a skilled 12th driver at your Club who can look at the car, and check your build in detail? I think that would help a lot. HTH
