SO i got the tracking and masking information from mocha. Just 5 second clip. I thought I could use particle world by attaching the producer to a null then to track the car...but this did not work because all the tracking data is on screen and so it looks like the particle is not moving with the car, just sitting on top and even using echo I could not make it have a streamer behind it. then I used the Tracker to create a camera so then I would have both the 3d space and the tracking data to work with...this was a bit closer but still not the quality I was hoping. for. I thought this would be an easy thing to do but I am having a hard time. got any ideas?
I think a 3D camera track is going to work better for this application; this will get you the camera-to-world-movement you need to get the particles to react right. Track in a solid to the ground plane, and apply a grid effect for reference. Then you can use keyframe animation to place your particle producer: the car will basically follow a straight path in space, so you can pretty easily keyframe it with just a few keyframes as long as you have a strong reference for the ground plane. Once you've got that, you can remove the grid.