The garage is not for household storage or a trash drop off because you don't want to walk all the way to the trash can. You can leave junk in the garage when I can build the engine in the living room.
Not a rule, but an observation: When working on a 30 year old car (my 87 turned 30!) it will speak to you if you listen. If something is going badly, it's telling you that you're doing it wrong.
They have character flaws just like us. I had a car that would break it's windshield if you looked at it wrong, while another could get hit by the space station and be fine.
Finally: I believe cars are Pagans. For the privilege of working on them, they demand a blood sacrifice. It's worth it.