If you look closely you can actually see the dust, but due to the heavy compression when using the HitFilm demo, you can't really see it. Here is a less compressed still:
Originally I did some tests with rigid body simulations of rocks being dragged as well, but due to the final res you wouldn't see it very well so I skipped it.
There are quite a few issues that I didn't have a chance to correct, but I am pretty happy with how it came out in the limited time I had (I'm currently doing some contract work for a short film, so time was limited)
Syntheyes for tracking
3ds Max for animating the car and rendering in Vray
Roto of my hand in Silhouette
Compositing in After Effects
I also photographed my own HDRI probes for light and reflections, and rebuilt the garage wall with projected images for accurate reflections as the car is pushed back.
I would have been able to do the compositing in HitFilm, except for the need of ReelSmart Motion Blur plugin.
I filmed the original sequence with a fast shutter speed to eliminate motionblur which helped with tracking and roto, and I rendered the car without motionblur to help speed things up.
I'll be doing a making of video too, to show more techniques in detail.