Describe a song that means something to you

The song I want to talk about is one my father used to play constantly on long drives when I was young, an old rock song from his university days that I must have heard a hundred times before I even understood the lyrics properly. I first heard it, as far as I can remember, on one specific road trip to visit my grandparents, crammed into the back seat with my sister, half asleep, with this song coming through the car's fairly terrible speakers. It's broadly about looking back on youth and not quite recognising the person you used to be, which meant absolutely nothing to me as a child and has started meaning quite a lot more to me only in the last few years. What makes it significant to me now isn't really the song on its own merits, though I do genuinely like it, it's that my father passed away a couple of years ago, and it's one of the few things that reliably brings him back in a very immediate, physical way — not a memory I have to reach for, more like something that just arrives the second the opening bars start. I don't play it often, actually, almost deliberately, because I think I'm slightly protective of how strong the reaction still is, and I'd rather it stayed that potent than wear it down through overuse. It's a strange kind of significance, tied more to circumstance than to the song itself.