looking for a specific wincest fic

hello there,
so I have quite a task for you.
i recently remembered a fic i read quite a while ago. i am sorry for making this hard on you but i remember very little from it.
the only thing that really stuck with me was am incredibly hot sex scene at the end of the story. i recall that they had sex on the edge of the road in the impala or outside of it. it was one of the best sex scenes i've ever read.
i also remember that it was a really good story, very well written with great characterizations and i think it had lots of pining and angst. (you know, the typical wincest stuff..). it may have been long or short, i don't really know. there weren't many kinks in the story, if any. it was just your typical wincest fic where they denied they had feelings for each other and than couldn't take it anymore and fucked. but they fucked only once in the story, right at the end, i think. and i think there was something about highway exits??? i don't know why but i think it was a pretty important element in the story. i also think it was a story by a pretty famous writer but i am far from sure about that. also, i read it on livejournal.
if you by any chance know what story i am talking about, i would be infinitely grateful to you for telling me.
sorry for being so vague but i just fail to remember exactly. i just know i really enjoyed the story and i'd love to read it again.