If you'd like, you can message them here:
https://www.facebook.com/pages/Free-Fall-un-film-de-Stephan-Lacant/1443310345902907A sequel: Unfortunately I only speak English & Spanish, not German
therefore I can't understand anything they're saying in the commentary nor in the deleted scenes (I own the German DVD Version of the film), but from what they were saying about a sequel, I mean I can take it as a joke but of course most people like us are unsure since we really want a sequel, so I think Stephen Lacant currently wouldn't want to produce a sequel, but maybe in the following years he might?
Perhaps another director may make a sequel for the film, that can happen. One of my favorite films, "Silent Hill" was made in 2006, and the director said he was planning to make a sequel but in the end dropped out. However another director decided to make the sequel and still utilized the same cast members and everything, which he did (but most people didn't like the movie either way).
But yes, the ending does leave an opening for a sequel, perhaps someone in the future may take advantage of this.
I enjoy reading the fanfictions that there are of the movie. Here are the best ones:
(
http://nocturneworld.com/free-fall-part-2-renaissance/,
http://archiveofourown.org/tags/Freier%20Fall%20%7C%20Free%20Fall%20(2013)/works,
https://www.fanfiction.net/movie/Free-Fall-Freier-Fall/ ).
If you read all of them (which were written by different people), I can assume that weeks/months pass by after the events of the first film, Marc gets the guts to try to find Kay, but has to take care of the baby that he had with Bettina since she can't do it herself (and leaves it to Marc). Marc gets Kay's address (since he is a policeman after all), goes to Kay's apartment (which is a several minutes/hours away) and finds him. Kay isn't interested at first until Marc explains to him the break up with Bettina, and in the end they get back together and possibly raise the child.
However, I'd prefer that there be a novel published as a sequel to the movie? That'd be pretty awesome.
Back to the film, In the scene were Marc & Kay were doing it on the car, I don't think lube needed to be involved since it was raining ( a lot ) and they were soaking wet. But I do agree that they are erotic and romantic.