Letting the sun shine in

Increased modularity and reduced mass and complexity are the focus of convertible-top system engineers.

Watching the hardtop roof of the 2007 BMW 3 Series convertible retract is like watching a mechanical ballet. With the push of a button, the car's greenhouse smoothly divides into three main sections, its panels quietly folding, flipping, and eventually nesting together in a neat package hidden within the trunk.

Total elapsed time of deployment: 22 seconds. And with the roof retracted, an impressively high 60% of the car's trunk volume is retained for cargo.