ok after having slept, I realised missed/misread a few posts and maybe started overthinking things while I was trying to explain. let me rephrase what I said, I don’t understand why everyone started discussing things as if she’s literally seeing the car (truck? whatever) at the moment of the sentence (or over the course of this time period).
Summary
in other words, this, I agree with:
but I think the discussion of how she can see the car doesn’t make sense since she’s not looking at the car and the カーテンを引いて is describing how her weekdays are passing, not the state of the curtains when she looks at the car
I think I got a bit confused with discussion of もの as well. 見る talking about the car makes sense but I think もの is nominalising the phrase/talking about the situation, not about the car
no it doesn’t. the whole verb phrase (which has its own subject) modifies the noun
so [こころが]カーテンを引いて、部屋で身を硬くしている as a whole modifies 平日 - こころ is sitting in a room, curtains drawn, feeling stressed. in this case it at least, it’s unambiguous that she’s the subject because it’s from her point of view and because weekdays can’t feel stressed. I took the liberty of adding the implicit subject and deleting a comma to try to make things clearer.
I think 気がする is a neutral way of saying something is creating a feeling/mood, but 気になる implies some sort of stronger, more personal emotional investment.