As a child of the 60's I remember watching American
cop / thrillers on telly where the way to kill someone
was to cut their brake lines . The car then went careering
down a convenient hill to destruction. Ignoring the fact
that no one ever seemed to just yank on the hand brake
it poses a question.
I drive an automatic and if I just let it run down a hill it
will change down to stop the car running away. In order
to go faster I have to actively press the accelerator. Would
60's ish American automatics actually run away like that
because their automatic gearboxes were different or was it
just artistic licence to have screeching tyres and fiery deaths.
It's only relatively recently (20 years?) that automatics have started doing a down-change on hills. Back in the 60's they were fairly simple devices - if you wanted a down-change you used the gear-lever.