[4U-GSE]

As others have pointed out "substantially impairs" is going to be the key language. You would have a clear cut case if the car was literally undrivable. I think you would also have a good argument if the condensation prevented the rear light from illuminating. Pennsylvania law requires that every vehicle "shall have at least one red stop lamp on each side of rear of vehicle, which shall be illuminated immediately upon application of the service brake." 67 Pa.Code. S175.66(e). If your rear light can't do this then the car would be unable to abide by Pennsylvania law and this would be a clear example of substantially impairs. Furthermore, your car would simply not pass inspection and you would not be legally able to drive your vehicle. No judge would rule against you if that was the case.

However, if your rear lights are still illuminating and are clearly visible (but maybe a even a little cloudy) I don't see a judge ruling that the condensation substantially impairs.

I would give the dealership a few more bites of the apple before hiring an attorney. I would even take my car to another dealership to try and fix the problem. It might be an annoyance but it's better than paying a couple hundred dollars in consultation fees.