Okay so looking at this most of the information we’re looking for says “Inherit Settings from Action”, which means we need to look at the IA_MoveCarForward file itself, because it’s just getting referenced here. We’re hopefully on the right track with this, though!
The “Set Throttle to a negative number” thing I mentioned is supposed to be done here as well- using “S” key should give a negated throttle number, which would be the same thing as what I was suggesting.