I've been thinking about working (I mean moving) cables between cars for a long time in LOTUS (which doesn't just hang into the other car nor is a self-coupled thing).
Here's the vehicle I cleary need this thing to happen:
Since this feature is not supported, I had to try a few tricks before I figured out something that would work, here's a video about it:
Of course the coupling models use mesh animations, otherwise it would not work - here's a few pictures about them with a gradiently coloured dummy texture:
First I was try to calculate from the radius of the rails, but that's not enough, because of the jumping of the cars.
What I did was this: I created an animation for the couplings - one for the front and one for the rear one. Since this vehicle has a non-moving coupling, I could use this animation (with "coupling" animation type) for this purpose - and for that I actually didn't give values for the rear coupling points but rather a bit higher, so the animations would work a bit more fluently. Then I made different animations for the different couplings, with X and Y coordinate translations, where I did calculate values from the radius of the rails, here's an example:
Yes, I did simplify the mathematical formulas for the sake of simplicity very much, please don't care about that 
Of course I had to fine-tune the animations so they would not collapse into each other (though it still lacks a few models and the cover plates are not animated yet). You can see the results in the video.
