It was not easy for me to rate this movie because the rating kept changing while I was watching it. It started as "good" (7/10), but then I felt some kind of discomfort without being able to understand what was bothering me, which made the movie so-so (6/10), until I realized suddenly that I simply disliked the guy.
The switch occurred when his sister asked him to stop filming and he kept going. When a woman says no, she does not want you to do it, when she asks you to stop and you keep doing it because you want to, I'm sorry but that's called rape. Of course it is not as bad but it's the spirit. This very scene is followed by the best scene-by far-in the whole movie: his sister explains how the filmmaker is using their mother's death to further his career, and that he is completely selfish about it, as if he owned her death. One can't help but wonder who is stupid enough to put such a truthful condemnation of a movie in the movie itself. As soon as his sister told him all this, he should have dropped the project altogether but no, the filmmaker apparently feels he is well above anything in this world, he is so smart, he is so proud to be a guest on the intellectual French Radio "France Culture" that he just discards such childish warnings (or, even better, put them in the movie as evidence of his intellectual honesty). These people are hicks, he's educated, he knows best, he'll do it anyway. In this day and age, this sounds pretty Trumpian.
Once you start "understanding" his personality, the movie turns sour pretty quickly. You feel that his grief is indeed just an excuse to speak about himself, - the little boy his mother loved the most, - you question the sincerity of the tears, and the testimonies of his family about his mother all fall flat. The title of the movie does not help: it is the name of old car model by French carmaker Renault. I can't wait for a movie about a genocide named after a hotel brand because the filmmaker slept in these hotels while shooting the documentary. To begin with, speaking about your grief in public does not sound very healthy, psychoanalytically speaking. The saddest people in the world don't rush to call people to film their pain, they just cry alone or in utter privacy. But you also cannot bind sincere grief with such superficial topics as how Renault-12 is the perfect car for drug smuggling, or the troubles you face with your inheritance. Finally I also had the impression that the filmmaker made fun of the people he met and showed in this movie. He seems to think: "How charmingly naive these country folks are! I absolutely need to capture their words to show my brilliant Parisian friends how backward they are, that'll be a good laugh." It is not as bad as that but, again, that's the spirit.
I am sure many people will enjoy this movie, especially those who share the mindset of the filmmaker, but his vanity and lack of compassion, his disrespect and shamelessness in exploiting people and events to his profit, as well as the bo-bo (bourgeois-bohème), smartass and see-how-cool-I-am attitude, ruined it for me. My final rating (5/10) is pretty generous and rewards the tiny bits that managed to make it into the movie against the filmmaker's will, in particular his sister's wisdom and sincerity, and the little cultural knowledge that transpired nonetheless. But, please, don't take my (humble) word and watch it yourself. Having lost my own mother in very similar circumstances, I may be biased in that I don't think grief should be a public affair, let alone a commercial one, but I may be weird.