When protection is key, it never hurts to be over prepared. That's why Ford is now offering Type IV ballistic panels for its Police Interceptor vehicles, which are based off the standard Taurus and Explorer models.
Type IV, as laid out by the US Department of Justice, refers to armor that can stop ".30 caliber armor piercing bullets with a specified mass of 10.8g and a velocity of 878 m/s ± 9.1 m/s." This option came about at the request of police departments across the country. As you can see in the two videos below, it's some damn strong armor.
Ford already offered Type III ballistic armor, which protected against handgun and non-piercing ammunition up to .30 caliber. The Type IV armor consists of two primary layers -- one that breaks the bullets apart upon impact, and a second layer that prevents fragments from entering the cabin.