Hello again, after all these second hand mechanics (4-5 of them I went to) voiced their opinions on the issues, especially the gas smell and abnormal fuel consumption, my father in law came this weekend to visit, also the toolbox i ordered arrived friday so it was the perfect time to check the engine cover and guess what, after we changed a gasket to thicken the seal, changed one bolt that was loose, now it doesn't rattle anymore and the smell is gone. It was because that engine cover was loose after all, and the gases were escaping the oil pit or whatever you call it (not good at english). This didn't make sense to me as to why a recipient that holds oil would release petrol gases, still doesn't, but whatever at least now it's fixed, will have to check if the fuel consumption also drops. I only have to clean my injectors and change the 2 lambda sensors to be sure i'm on the track, even though the sensors most likely will fail again after a few months.
So i kept the engine cover after all @TMB and also thanks for the video that covers how to seal my rear doors, after this rain stops I will get to work now that I also have new tools (including torx)
@GordonSuperbmk2 that was the my decision after all these "mechanics" didn't know the issue, to go to a skoda dealer and have the actual tester used that shows everything, but glad i didn't have to now
All that remains are the air vents from under the front seats, facing the rear passengers feet. I really wanna improvise something, maybe like a bend made out of plastic, so the mats don't block the vents anymore and they're actual functioning..