Keeping it in my car is not safe, especially these days with the 100s of cars being stolen.  (So much for relying on the police, eh?)  For one, guns ARE NOT TOYS.  If someone is treating a gun as a toy, that might be the time to call the police.  

As with any weapon, you need training.  (That includes your hand-to-hand combat -- and I'm not trained in that.)  

How do you disarm a shooter without a gun and a mass of bodies running around?