A single .45 slug went through the rear of this compact, through the seats, and into the dash.
But the regulator is the only part of a car door that's going to stop a bullet. Most handgun rounds will sail through both sides of the light sheet metal door construction if the regulator is not encountered. Accordingly, if you are forced to fire into a car door, aim high or low and miss the regulator. Most regulators are located high and to the front in average vehicles.
Surprisingly, compact vehicles may offer as much protection from bullets as larger vehicles. Compacts are as heavily braced as larger models, and full-size vehicles often have larger areas that are not braced and therefore are more vulnerable.
A .30-30 hits in a quarter panel.
The rear quarter panels of most vehicles are covered with lightweight sheet metal and offer little obstruction to bullets. Firing into a typical sedan, we discovered that pistol rounds will usually sail through both quarters unless they strike a spare tire or a jack handle. However, there were exceptions. Some large four-door vehicles have numerous braces in the rear section that will stop handgun bullets.
Firing from dead behind several vehicles yielded some unexpected results. Almost without exception, handgun bullets fired from directly behind the vehicle continued on to the passenger compartment in cars. The deck lid and rear glass offered little in the way of an impediment. Bullets shot directly into the tag bracket penetrated the rear and front seat, often imbedding themselves in the dash.
The rear of a pickup truck is a formidable obstacle for small arms fire. In our tests, tailgates stopped handgun bullets, and if the tailgate was down or removed, most handgun bullets were stopped by the front of the truck bed.
SUVs and station wagons also offer challenges for officers shooting at them from behind. The rear tailgates of these vehicles are much more resistant to penetration than car doors. Generally heavier construction and the larger, more complex window regulators make these vehicles relative "tanks" from the rear.
In the case of full-size station wagons, only the .357 SiG, with jacketed hollowpoint ammunition, made a good showing. The only other round that gave similar performance was the full-metal- jacket .40 S&W round. During the test, the roundnose .40 exhibited penetration superior to any other round, except the .357 SiG. This illustrates that officers issued the .40 caliber might consider carrying a spare magazine loaded with full-metal-jacket ammunition for such emergencies.
Finally, while the metal work in the rear of station wagons and SUVs is tough, the glass isn't. Most rear glass in automobiles and light trucks shatters as easily as the door glass. Our tests show that a double-tap is ideal for shooting a target in the rear of a vehicle through the glass. Shoot once to shatter the glass and again to neutralize the target.
Tires and Wheels
The vulnerability of a tire is determined by where you hit it. That's as true for bullets as it is for roofing nails.
To take out a car tire, any full-power round fired into the sidewall will do the job. Any caliber with adequate penetration will induce a leak, but the hole often closes with only slow seepage. If the car were traveling at high speed the dynamics might be different, but a single 9mm hole would leave a tire up for as much as a minute. The .45 and .357 SiG were better, but by a small margin. Shotgun buckshot and slugs performed the best during this test.
A seldom seen shot might be firing from dead forward or from dead to the rear into the tread of the tire. Here, we had a surprise. The tread stopped most bullets. In fact, we spotted the base of 9mm bullets in the tread after firing from this angle.
As for wheels, steel rims uniformly stopped all handgun bullets with only a lead smudge left on the wheel. Aluminum wheels sometimes were holed, but the wheels' integrity was not affected. It seems that steel wheels would present ricochet problems, and this shot is not something we should take. There is no profit in it.
9mm hollowpoints fired at close range did serious damage to the sheet metal on the rear quarter of this Cadillac.
If you need to shoot at a vehicle with a handgun, a .357 Magnum is a good choice. Unfortunately, the .357 Magnum is not often seen in many police holsters anymore. Of the common police sidearms, the .357 SiG and .40 caliber S&W were the best overall performers, and the .45 ACP represents a good balance of power and controllability; with the best wound potential and proven record in critical incidents. The 9mm was definitely the least impressive cartridge in this test.
A 12-gauge shotgun proved moderately effective when loaded with buckshot. We have read published reports that indicate 00 buck could not be counted on to fully penetrate vehicle windshields. But you can't prove it by us. Firing from seven yards, on many occasions 00 buck not only penetrated the windshield, the rear glass was blown out by a pellet or two. As range increases buckshot is much less effective, but at short range it should not be underrated. However, as effective as it is on glass, radiators, and tires, buckshot is a substandard penetrator of sheet metal.
Another shotgun option in our test was the QB slug. This is one of a new generation of 12-gauge slugs that offers superior accuracy and penetration. This slug excelled in light cover penetration, overall outperforming all handgun ammunition.
The .223 rifle is often lauded as the ideal urban rifle caliber, with low chance of ricochet, good wound potential, and excellent accuracy. And with some reservations, it does a good job on cars.
Car glass is hard on the .223. But light metal penetration was adequate, better than any handgun caliber. At moderate range, the .223 rifle shot extremely low, and this will have to be accounted for. A 6- or 8-inch strike under the point of aim at seven yards was common. This is to be expected of a weapon intended for long range use.
What we discovered during this test is that no matter what caliber or weapon you use, vehicles are actually quite resilient against bullets. Consequently, the most effective action for an officer when he or she must fire at a car is to maintain cover and deliver fire to the areas of a vehicle that are most vulnerable.
When you are under fire, survival often depends on finding cover, and since you spend all day in your patrol car, it's likely to be your only cover in a gunfight. But does your car really offer you protection from high-velocity lead? The answer is a resounding maybe.
Put simply, the quality of cover provided by a patrol vehicle depends on the vehicle and where you choose to take refuge inside or behind it.
If you are trapped inside your car in a gunfight, never bet your life on standard safety glass. Yes, windshields have been known to stop bullets, but that says more about the quality of the bullets than the strength of the glass. While our tests involving real cars demonstrated failures of certain loads to penetrate car glass, including 9mm and .45 ACP hollowpoints, these bullets were so lightly constructed the jacket stopped in the glass and the core simply fell in the front seat. That doesn't mean that automotive glass is an effective barrier to bullets.
Outside of your car, your best cover is to put the engine between you and your attacker. This is not a 100 percent secure position (nothing is), but the heavy metal components of the engine are the most bullet-resistant parts of any motor vehicle. Our testing using actual cars shows that small arms fire is largely ineffective against engine blocks.
When you can't put the engine between you and the bad guys, your next best cover on a standard patrol car is the doors. However, that doesn't mean that doors offer good cover. Bullets from even 9mm pistols will slice right through them unless they strike the stamped steel parts of the regulator.
Other than behind the windshield, the weakest point on your patrol is the rear quarter. In cars with long rear sections, small arms fire will likely penetrate both sides. The only strong points are the steel braces, and they are few and far apart in many patrol cars. Surprisingly, the rears of some compact cars actually offer more cover than full-size sedans because the braces are more densely packed into a smaller area. Bullets fired into the rears of these cars are more likely to strike steel. In our test vehicles, a couple of quarters in short vehicles were braced so heavily a .30-30 bullet did not penetrate both.
R.K. Campbell has 23 years of experience in law enforcement. He holds a degree in criminal justice and has served in most police capacities.