I too would love to have a manual, allbeit, a pdf for me to printout myself seems enough.
But it'd have to cointain detailed setup descriptions (what does which slider do and how will it effect the car, concerning game physiks, and not RL physics [if they defer, that is])
All the car specs + a fictional history of both the brand and the cartype.
All the track specs + fictional background
a history of LFS. How was it born, in which way did the project develop (and more inteesting: which parts turned out to be completely different than intended).
Oh well, I just like well written manuals and am all for ones whic offer background info and fiction which is beyond the simple explanation of functions.
But as producing such a handbook is quite of an effort, I would neither be surprised nor dissapointed, if such a thing is never published