There is no "abandoned getaway car" in the Wiegman film. The "getaway" car had not arrived when Wiegman filmed the Island.
Dear Sonderführer Storing,
Yes, there is.
In the pertinent Wiegman frames, part (James Hackerott says it's a middle part) of your "Abandoned Getaway Car" is visually merged with a light-colored car parked on the other side of Elm Street Extension.
Now that's been established, we're trying to figure out exactly which of the light-colored cars parked on the other side of Elm Street Extension in various photographs and films -- taken before, during, and after the shooting -- is the one in Wiegman that's merging with your light-colored 1958 Pontiac Bonneville parked next to the "Island."
When I say "visually merging" with your "Getaway Car" I mean perhaps just the rear part (or, more likely and as James Hackerott prefers -- a farther forward part) of said 1958 Pontiac Bonneville "Getaway Car" is overlapping the light-colored car in the background. Whether we're seeing the rear part or the middle part of your "Getaway Car," what really "seals the deal" that it really IS your 1958 Pontiac Bonneville Getaway Car is the distinctive 1958 Pontiac Bonneville "jet exhaust" design on its side, plus the fact that its passenger's-side rear tire and its passenger's-side front tire and [fill in the blank] are also visible in certain Wiegman frames.
Perhaps the light-colored car that your "Getaway Car" is visually overlapping in Wiegman is one of those two light-colored cars that were still parked next to the TSBD and
behind Inspector Sawyer's car when Amos Euins was put in it a few minutes after the assassination in the National Geographic documentary you turned me onto a few months ago!
Warning: One of those two light-colored cars
behind Inspector Sawyers' car is barely visible in said documentary.
-- Tom