A good way to test stability differences is to get into a push-up position. With your hands and feet both spread, have someone push on your hip. The lower you are to the floor the less likely they can push you over. So if you raise your butt higher, it will be easier to push you over. To compare to a three wheeler, put your feet together. Again, the closer to the floor the more stable. Note: Pushing on the hip represents a force similar to turning a corner in a vehicle. Granted, this is a simple demonstration, but it shows the basic physics involved as a starting point. Like others have said, steering geometry, stability systems, etc., are involved also. The Elio is long and low, and with the wide wheelbase should prove to be pretty stable. Some of the new three wheelers look too tall and short to be nearly as stable as the Elio.