I have the coil suspension and it is not like what you describe at all. Something may be wrong with the suspension in your car. One oddball thing that has been reported is that if the hatch is not properly snug it can affect the way the car handles bumps. Or, perhaps, something as simple as shocks needing replacement. I like my coil suspension a lot....I had test driven three Model S. However, I did not realize that all of them had air suspension, so I just assumed that's how the Model S rides. When I bought my pre-loved Model S, I knew that it didn't have the air suspension, but didn't realize on the short test drive how annoying the standard suspension would be. In fact, the car is so stiff that when I drive it alone, it hops and bops over every litle bump, until I reacy a rare 85 mph. If I ever buy another S, it will have to have air suspension.