In the video they say the cars are "micromachine sized", I asked them about that cause MMs tend to vary a little in size.
They got back to me saying at this early stage the pedestrians they were considering were a similar size to the larger Epic infantry mini, the likes of ogryns and nobs.
I think that makes it about 10mm scale maybe?
Though saying that with it being a future post apoc/scifi type setting enclosed vehicles of any scale close to that would probably look fine, things only start maybe going a bit weird when you have models on foot and in vehicles that might be all different sizes.