[papadoc1945]

I like the idea of a harpoon. Unfortunately nothing you stick into sheetmetal is going to stop a car/truck/van. An EXPLOSIVE harpoon, on the other hand....

[Congressman Billybob]

Imagine a sharply pointed head with fins, about the same as a molly bolt, that can be fired through sheet metal to attach a high-strength cable to the subject vehicle. That will be enough to pull the vehicle sideways to the curb, or drag it to a stop from behind.

John

[Disambiguator]

You don't need explosive, just EMP. All newer vehicles are laden with electronics that can fry, and when they do, the vehicles shut down completely.