Changing train car length

[Phasma Felis]

As discussed here, train cars are shorter when oriented north-south than east-west. I'd like to fix that. I understand that the perspective makes the sprites shorter north-south, but I'd rather have the cars appear to be further apart visually and be the same length in-game.

I figured the Lua code would have some sort of X-length and Y-length, or perhaps a scale factor, but looking at the "diesel-locomotive" and "cargo-wagon" entities in entities.lua, I don't see anything like that. connection_distance and joint_distance appear to apply equally on the X and Y axes, collision_box rotates with the car, and (unsurprisingly) changing the frame_width/frame_height values under pictures has no mechanical effect. Am I missing something? Is this value stored somewhere else, or is it maybe hardcoded?

[Rseding91]

It's hard coded into the Train AI and not adjustable through prototypes.