Erm,
Ok… what about…..
Using trapcode Particular (or Particle Illusion) to create a smoke curl (as viewed from rear), use blurring to `smudge` the smoke..
Then Mirror the layer so you have the funnel. Maybe off set one and scale it slightly to make it not so mirror image.
Once you are happy with the setup..
Pre-comp it and duplicate the pre-comp ( how many time you require to get required length ) through z space slightly staggered in timing. The finished effect should give you that look. If you make all layers 3d and use a camera moving along you could swing /pan along it..
Or much easier might be to use a 3d app like 3ds max to create and animate the trail then mirror it for both sides..