We take a look at the spring / car suspension system I showed a few days ago, and we make a 3-point constraint using ICE nodes.
I found the spring equation on Wikipedia, and I hope I explained it correctly. I'm not a physics expert...
Please keep in mind that the suspension system is extremely basic. I put it together over the course of about 40 minutes, just to see if it would work.
An obvious improvement would be to ensure that the four top particles always stay within one plane (because the car body is rigid). After all, it's not the wheels that pull the car down, it's the car that pushes the wheels down. So in actuality, there can be situations where a wheel does not touch the ground at all, while in my current system they always do.
Another obvious addition would be the automatic calculation of wheel rotation, steering abilities etc. etc.