"Believe" whatever you want, but as is plain for everyone here to see, there is no evidence of any kind to support said belief as it pertains to imaginary assassins making their "getaway."
That car is Not on the Wiegman Film. 20 seconds later it is on the Darnell/Couch Films parked in a "NO PARKING At Any Time" zone alongside the Island. This means that same car was traveling down the Elm St Ext as the JFK Limo was under fire. Obviously, the occupant(s) of that car were Not in Dealey Plaza to see the JFK Limo and/or the JFK motorcade. Otherwise, they would Not be inside a moving car while the JFK Limo was traveling down Elm St. And that same car, is still parked in that same position, alongside the Island, when Dealey Plaza was completely cleared for CSI work. This was 3+ Hrs after the kill shot. The streets leading into Dealey Plaza were sealed off before the JFK Motorcade arrived at Dealey Plaza. This means that "getaway" car had to be inside Dealey Plaza well before the motorcade arrived. There is no innocent explanation for a car to be traveling down the Elm St Ext while the JFK Limo was under fire, then park alongside the Island in a clearly posted "NO PARKING At Any Time" zone, and then remain in that same parked position for 3+ Hrs.