It's a handful of dialogue-free kiddie mini-episodes about guinea pig cars. They run around and squeak at each other in authentic guinea pig voices. (Guinea pigs have unexpressive bodies and faces, but they're noisy little buggers with a surprising vocal range. A group of happy guinea pigs sounds rather lovely, actually.)
The show's adorable and it's been picked up by Netflix.
For what it's worth, Tomoko and I kept guinea pigs for years. "Guinea pig" in Japanese is "morumotto", transliterating the Dutch word "marmot", but Japanese words often get abbreviated and Tomoko always just said "moru". (R and L are the same in Japanese, of course, so "molcar" is "moru car".) As for the title's "pui pui", that's the Japanese onomatopoeia for a guinea pig's squeaks.
I enjoyed the show. Using real guinea pig voices is brilliant, while in addition they've only used the sounds of happy ones. No anger, fear, pain, etc. If you know guinea pigs, that's another thing that makes it nice to listen to. I did, though, slightly dislike seeing their live-action drivers. (It's done in stop-motion live-action, shooting real actors with an extremely limited frame rate to look similarly hand-animated.) It breaks the spell, especially when they're hamming it up. The lady in ep.1 is a bit annoying, although I quite liked the litterbug actor in ep.4. He actually manages to pull off his broad performance, if that's the word. The show can be divided roughly into two halves: (a) eps.1-4, which have those inside-car shots I disliked, and (b) eps.5-11, which are more satisfying and don't go inside the molcars at all. A molcar in these episodes is basically just a living stuffed toy with a guinea pig's personality, but with wheels instead of legs.
Ep.12 then has an inside-car shot again, but only right at the start and for about five seconds. She's lifted out and lain on the sofa to sleep, after which she becomes an Action Man doll, like all other exterior-shot humans in this series. I have no objection to the dolls.
Each episode tells a complete, cute little story. That's impressive in three minutes. (Strictly speaking, two minutes forty seconds.) They're quite often parodies. There's a zombie horde, a Indiana Jones molcar who needs persuading to go into a car wash and a spy mission with a flying robot shark that shoots down a helicopter gunship. The molcar version of Back to the Future is particularly clever, I think, because the original car is instantly recognisable and looks quite funny in this molcar version. (The episode has nothing to do with the original film's plot, though.)
My favourite bits were the ones where the molcars behave like real guinea pigs. The car race in ep.5 is great because that's exactly how guinea pigs would behave. Race? Carrots? Carrots! Two guinea pigs both pulling at the same bit of food is so true. I also enjoyed the molcar doing a poo to blow up the flying robot shark.
It's cute and fun. Tomoko and Misaki watched it too.