[Patrick C]

As I recall there are examples of comparisons of the Nix and Z films frame by frame and there are no discrepancies in limo speed.

I would accept totally that if for example Nix showed a slow down and Z did not then yes something is not right - aside from an error in speed of the film shown.

I also agree that the Nix film does appear to make the slow down more apparent - perhaps because he did not capture the whole lower Elm St section as did Zapruder - Nix section 2 starts in the middle of the slow down which may create the impression that the car moves more slowly than in the Z film.

It is clear to me that the limo did not stop, it simply slowed right down.