Thanks all :)
Here are some answers:
Camera is simple - I just manually positioned camera every 40th frame in a way it would make a nice still image, then smooth interpolated between the keyframes, tweaked path so it doesn't fly through any of the trees, and added a slight noise to translation and rotation using noise float controllers.
Trees were mostly models from iCube, but i completely remade materials and added some per-instance texture randomization, tessellated bottom of the trunks further using MeshSmooth tool in Editable Poly, and used displace modifier with same texture as the one used for bump on the trunk. It adds 200-400k more polygons to the tree model, but it's usually worth it.
Grass and twigs were just clumps i manually made. As well as tree stubs... just very simple manual models.
Scattering was done with forestpack. I drawn just a simple bitmap of forest road as well as some small footpaths branching from the main road, and then used them as distribution maps for some forest, or scale map for grass distribution forest.
Terrain material is just a few dirt textures mixed together, with different tiling. For example 10*10 tiling dirt texture mixed with 1*1 tiling 50:50, and that goes into another mix slot mixed with another 5*5 tiled dirt texture, and the mix amount map is just random screenshot of random google maps location somewhere with cranked up contrast. This gives usually enough detail to both hide tiling from distance, and look detailed enough from up close. Subtle displacement takes care of the rest.
VolumeMTL is not that fast, but it's finally usable with single bounce only feature in daily builds. I re-saved the scene, put 100% black material as override for everything, and then used VolumeMTL with single bounce only. This way i got a quick volumetric pass i comped over in fusion.
As for the car animation... there were quite a few iterations on that. It just kept looking too rigid, so we were constantly softening the suspension, until we came up with this.
As for the rendertime. It was 55 minutes/frame on our render farm which mostly consist of dual xeon blades. IDK exact config, but i know on my workstation it was 1h 30m for fullHD frame on i7 3930k. Both DoF and MB are rendered, and GI was PT+PT. Took 100 passes to come out clean enough.
