[pothole]

Maurice, if you look at how the clam is hinged and how the roof sits under it, I simply do not believe that it's possible for it to pop up at speed. Hitting bumps does not cause the clam to jump up more than a fraction due to the hinging which requires a backwards motion. Plus, the higher the clam moves the more it's going to be pushed down by the passing air. It's just not ever going to happen at any speed.

I too wouldn't go under a car on a hydraulic jack. But I do not believe there is any chance of the roof popping open at speed.