Oh yes, that’s definitely a big part of it. I didn’t touch on it here but the springs’ compression is affected by the normal force in an emergent way via Unity’s physics.
Remember my last post about collider hell? That was because the springs were too weak. When the car was climbing a hill and slamming into a curve (or taking a banked curve, or a loop, any concave surface at high speed) the normal force was compressing the springs past their limit and the car’s body was scraping the ground.
So yes, it’s in the equation, just implicitly and not in a way that I need to calculate explicitly at runtime. I can just look at the springs’ compression and get an idea of it.