I have a 2018 model 3 and my gf just got a 2020 model y. I am not sure if the 2020 model 3 has some or all the let downs that I am about to mention. First is the model y does not come with auto dimming side mirrors, this is a huge let down because most modern cars run bright LED lights and being blinded sucks. Second is I find the glass roof in the model y lets in a lot more heat compared to the model 3. Then there is the cheap hard plastic used on the bottom of the doors where the side cup holders and pocket space is, in the model 3 they use a soft touch injection molded plastic. This may be a bad car issue but the doors and frunk on the model y are significantly harder to close, literally have to slam them shut. This may be another issue in the car but in the model 3 I can say "open glove box" and it will open, the model y does not recognize the command. This is overall a lot of small things in the grand scheme of things, because the model y is fantastic and it's a blast to drive, and I understand there might be some cost cutting to be had because of the targeted price point and the additional features and materials used to build the model y.