[LAP1DOUG]

I found that it is very difficult to get the cap tight enough by hand to seal well. It seems that the rubber seal causes some friction as it starts to seat and makes it difficult to turn.

I was having similar symptoms, and I lubricated the rubber seal with soapy water, which allowed the cap to turn another 30 - 40 degrees of rotation, and sealed everything up fine with no more mist / condensation on the trunk lid, and no leaks.

Good luck.