If you're stuck in a sinking car, or outside your car and desperately need to get inside, you have plenty of ways to break that window, but one of the best might be right there in your car anyway—a simple sparkplug will do the trick with ease.'ve seen people do this with the sparkplug ceramic, and others do it with the point of the sparkplug itself, but throwing the ceramic at the window is probably safer from the outside (since the glass is designed to shatter outwards if it breaks).