Annelise Meineche – Uden en trævl aka Without a Stitch (1968)

When a high-school girl complains of her inability to reach sexual
climax, her doctor suggests that she keep a diary of her sexual
encounters. She does just that and soon finds herself caught up in
a sexual merry-go-round that includes making a hardcore porno film
in Sweden, an escapade with a German sadist and a lesbian
encounter.

Erwin C. Dietrich - Blutjunge Verführerinnen 3 aka The Calendar Girls (1972)

A hitchhiking runaway tells the man who picks her up about her friends' sexual escapades.

IMDb comment:
Delicious sex scenes with Ingrid Steeger, towards the end are of a different order.
For the most part the sex scenes are awkward and the links abysmal while the ongoing devise whereby the fat guy provider the lift gets told the various tales adds nothing. However the delicious sex scenes with Ingrid Steeger, towards the end are of a different order altogether and the final potentially gross scene with the very large and ageing forest ranger a thing of wonder. Why couldn't Steeger have just done all the scenes? She is not well supported here and it looks like a case of relying a little too heavily on her ability to carry the film. Still, as I say the film is saved in the last half hour and whilst I never want to see most of this little number again, I am sure I could delight again in that fine reel or two.