I think I understand the reasoning now, thanks!
Lowering the CoG is something I was recommended to do to combat the tendency to topple over, and it obviously makes sense that it helps. If the behavior I can see now is just an artifact of lowering the CoG too far, I’m not sure how I’m supposed to make this car stable enough to be of any use (excluding obvious solutions like using a mesh that has a naturally better ratio of CoG position and track width/distance between wheels).
Bummer. But at least it sort of makes sense now.