I use 2 container because i have to fluid emiter with diffrent vel and noise settings have 2 sourceapply stil learning this new node has alot of options, maybe can be only one but for now this is setup.
I didnt try to use fluid vel field for cars i made everything in sim.
Really nice work. I see on the vimeo link that simulation lasts about 2hrs (not so bad, thinking of realflow times). I'd like to know which hardware you are using.