Curtain

This is a device to stop criminal suspects who are trying to evade capture by fleeing in cars. It will work best on city freeways.

The device could be attached to the bottom of any bridge that crosses over the roadway, or to a specially built framework.

The device is activated by remote control from a police car or other civil authority. Hopefully, the device will be activated just before the target vehicle reaches it.

When activated, a huge sheet of Mylar, Tyvek, or similar material will suddenly drop down like a curtain to obstruct the roadway, so that the fleeing car is forced to either stop or crash through it. The sheet is lightweight enough that it will not damage the vehicle. (It could be perforated so that it breaks apart in large chunks.) It is coated with a non-permanent adhesive (something like Post-it notes or flypaper) so that, if a car crashes through it, it sticks to the vehicle, especially the windshield, and obstructs the driver's view. Then, unless the driver is a complete idiot, he will immediately stop—or else drive so erratically that he will soon crash or be captured.

Hopefully, the material will also wrap around the vehicle sufficiently to impede the driver from exiting the vehicle and fleeing on foot.

In any case, the material can be easily peeled off from the outside, allowing officers to arrest the driver, or allowing the driver to go on his way if he is not wanted.