This, I will admit, I am by no means an expert on.
Let's look at some crimes that occur on, in, or near vehicles.
-Sexual Assault
-Robbery to include carjacking
-Assault
-Murder
-Kidnapping
And I know what you're thinking...
"I'm a black belt..." or "I carry xxxx gun..." or "...yyyy knife..." or "...zzzz other weapon..." and I'll tell you that unless you've trained using those martial arts skills or weapons inside a vehicle... THEY ARE NOT VERY USEFUL!