(I) watched – the trees sliding past – us blur into each other. Rush, rush, rush said the air as we approached the horizon The sky was an opaque grey; (looked) like a cement wall. I imagined an invisible giant placing the earth into a concrete box. I wondered if I had ever been a blur in(to) the scenery – (the sky) – for someone watching me through a car window. What was meant to be a comforting hand on my shoulder (instead) felt stiff and contained, it felt like fingers – were – made (of) plastic I wondered if parts of me were perhaps stuck on a landscape like smeared paint – mistakes – I wondered if (you) my love had ever driven past me.
If the title hasn't hinted enough -> read the poem as it is -> (read only what is inside the brackets) -> – read only what is between the dashes – -> eliminate the dashes and brackets (or if you want, eliminate only the dashes, then only the brackets, then both)