[TangoLimaSierra]

...whole windshield sticker that won't come off could stop a car in its tracks.

If they start doing this use something like RainX. It's silicone based so I'm betting nothing will stick. Probably need to reapply every couple of days.

Now I guess I need to test that.

[Cletus.D.Yokel]

Just throw one of these in the glove box.
Available at hardware stores everywhere, in the paint aisle.
Makes an impressive weapon, too...4-inches of exposed razor-edge knife: