How Police Cars Work

Two new police cruisers ­on display at the New York City Police Department headquarters. See ­more police pictures.
AP Photo/Mary Altaffer ­­

Most of us have a love/hate relationship with police cars. We hate seeing them in the rear-view mirror when we're going a little too fast on the highway, but they can also be a welcome sight when we're in need of assistance. Officers use police cars for many things: to patrol their beats, to chase suspects, to store their gear, to restrain criminals and even as communications links. Some specialized police vehicles do even more than that.

­But what makes a police car different from other cars on the street? It takes a lot more than just some flashing lights on the roof and a two-way radio. Modern police cars are significantly more rugged than their civilian counterparts, and they hold a battery of high-tech (and low-tech) equipment.­

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From high-

horsepower engines to special restraint systems for unruly crooks, police cars are a breed apart. In this article, we'll find out h­ow they're made, wh­at they're capable of, and what equipment they use to get the job done. We'll also take a look at the history of police cars.


Police Car Models

All po­lice cars are based on standard production models of civilian cars, except in rare cases where military vehicles are converted for police use. There are no companies making cars solely for use as police cars, with a few very rare exceptions. Instead, car companies make special "interceptor" or "police" versions of certain models -- typically large sedans. In addition, police departments occasionally purchase civilian vehicles that fit their particular needs and customize them for a specific use.

The most common police vehicles in North America are the Ford Crown Victoria, the Chevrolet Caprice or Impala, and, in recent years, the Dodge Charger. All of these fit the typical police car profile -- large sedans with plenty of room in the trunk for equipment, lots of room in the back seat for suspects and a relatively large engine. Countries outside of North America typically use domestic cars of a similar nature: For example, in Italy, a police department may choose to use a Fiat as a service vehicle while in Germany, a BMW may be a logical choice.

There are lots of police vehicles that don't fit the standard patrol car mold, however. For example, SUVs and pickup trucks are often used in areas with rough terrain, or in situations when the officers need to carry around a lot of extra equipment. Police departments have even been known to use more exotic cars. Sports cars are sometimes used as special chase vehicles -- police Camaros, Mustangs and even Corvettes are not unheard of. In Italy, there are even a few police Lamborghinis. At one time, these Italian exotics were unique custom police cars, but recently, Lamborghini started equipping its Gallardo models for police work at the factory [source: Biggs]. These ostentatious police cars are usually used as public relations tools rather than working patrol cars, and in many cases they were originally confiscated by the department during drug raids [source: Jones]. However, it's reported that the Italians use their Gallardos for daily patrol duties.

Next, we'll get under the hood of a police car and find out what sets it apart from the average car.

Police Car Components

The Hemi engine is standard issue in the Dodge Magnum police car package that debuted in September 2005 for the 2006 model year.
The Hemi engine is standard issue in the Dodge Magnum police car package that debuted in September 2005 for the 2006 model year.
AP Photo/Dodge

Take a moment to consider the kind of abuse a police car has to endure. At one extreme, it might be pushed to the very limits of its performance, chasing fleeing suspects at speeds greater than 100 mph (161 kilometers per hour). It might be driven over rough terrain, smashed into by angry criminals, or used as a battering ram by the officer behind the wheel.

At the other end of the spectrum, a police car could spend all day sitting in one place, idling for hour after hour or cruising along at low speeds as the officer waits for speeders or patrols a suburban neighborhood. A police car has to do this under relentless summer sun and in the depths of frigid winter nights, and it often has to switch from "idle" to "action" in a split second. While doing all this, the car needs to provide enough power for the radio systems, a computer, lights, sirens and any other equipment that might be installed on the car. As if all that weren't enough, police cars are heavy -- about 1,000 pounds (454 kilograms) heavier than their civilian counterparts, depending on the model and what options are installed. It's important to remember that the primary goal in designing the average police car is not power or performance, but durability.

To get the job done, a police car needs some heavy-duty components:

  • High-performance engines - Police departments have to strike a balance between power and economy. While a few cars may be equipped with V8 engines for chases or highway work, the bulk of the patrol fleet will usually have V6 engines, which use less fuel. In either case, police cars require engines that can endure severe use.
  • Upgraded alternator - The alternator takes energy from the running engine and coverts it into electricity to run lights, sirens and other electrical systems and equipment. Police cars use alternators that can crank out 225 amps or more. A typical civilian car's alternator generates less than 100 amps [source: American Power Systems, Inc.]. A heavy-duty battery also bolsters the electrical system.
  • Coolers - Civilian cars mostly rely on their radiator to provide cooling, but the extreme conditions police cars are subjected to create the need for dedicated cooling systems through the vehicle. Transmission and oil coolers are standard equipment, along with a beefed-up radiator and a larger fan. Sometimes a power steering cooler might be included as well.
  • Heavy duty suspension and brakes - The added weight of all the police options, along with the high performance maneuvers police cars are sometimes required to perform, require upgrades of the suspension and brakes. Larger, stronger brakes, heavier springs, shocks and stabilizer bars help police cars turn and stop smoothly despite their added bulk.
  • Other heavy duty components - The drive shaft, u-joints, frame mounts, wheels and exhaust system are all sturdier than those in a civilian car [source: McCord].

In the next section, we'll find out what other special equipment is installed in a police car to help officers do their jobs.


Police Car Equipment

The interior of a Michigan State Police Dodge Charger
The interior of a Michigan State Police Dodge Charger
AP Photo/Paul Sancya

When a manufacturer assembles a "police special" at the factory, they often don't actually install a lot of the equipment that officers will ultimately need in the car. That's because each police department has its own policies and needs, and even within a department, different cars may be outfitted with different gear. Therefore, the departments handle the installation themselves, either through a local shop or, if the department is large enough, using their own mechanics.

One of the first things people notice about a police car is the paint scheme. In the United States, there is no unified criteria or standard for painting police cars, so each state, agency or municipality determines how its cars will be painted. The point of the paint job is to make the car look distinctive and easy to see, but this can range from the classic "black and white" look, common in the 1950s and '60s, to more elaborate paint schemes with stripes and lettering.

The light bar on the roof is another key element, and the roof is reinforced at the factory to hold the extra weight of the bar. Modern light bars are streamlined, and contain banks of multiple lights in red, blue and white, all of which spin and pulse in patterns which are tough to miss, even in daylight.

The siren noise made by a police car is generated by a fan that pushes pulses of air through specially shaped holes in a small drum. The resulting sound is incredibly loud. Modern siren systems can automatically control the air pulses to generate a variety of sounds, such as the hi-lo (commonly used in Europe), the yelp, the wail, and the loud squawking sound of the air horn. You can listen to some police sirens sound demonstrations at

Police use wideband radios that broadcast on special frequency ranges set aside for their use in the VHF and UHF bands. Officers can also route the radio microphone through speakers integrated into the siren, allowing them to use it as a public address system.

Instead of an arm rest, modern police cars have a swivel mount for a laptop computer. Officers use this computer to access a number of databases, to fill out paperwork and record witness statements while they're still at the scene. The computer can also be used to upload digital photos they've taken of crime scenes. Some departments utilize wireless technology, so officers can check license plate numbers or suspect IDs against a database of stolen cars or outstanding warrants. They can even get a suspect's criminal record and photograph on screen right in front of them, without having to relay information through a dispatcher.

Have you ever wondered what's in the back seat of a police car? Find out in the next section.

Inside a Police Car

The back seat of a police car is­ not comfortable. For one thing, it is made of hard plastic or smooth vinyl, so it can be easily cleaned (the back seats of cop cars end up covered in a surprising variety of human bodily fluids). In some cars, the seat is cramped, forcing suspects to sit very low or bend their heads down. To some extent, this is done to psychologically suppress people in the back seat, but it also makes it tougher to gain leverage or momentum if someone tries to launch an attack.

What protects police officers in the front seat from violent prisoners in the back seat? Some combination of a steel mesh cage and bulletproof glass is installed to keep them safe, along with steel plating behind the seats to prevent stabbings. The rear windows are reinforced with a wire mesh -- although they're not usually bulletproof. While strong, they can be kicked out by a forceful enough person [source: Hiltunen]. Needless to say, the rear doors of a police car cannot be unlocked from the inside.

In the trunk of a patrol car, officers store any bulky equipment they might need at a crime scene. This can include bulletproof vests or other body armor, a shotgun, first aid kit, a portable defibrillator, specialized tools (such as bolt cutters), or other gear specific to that officer's training and assignment.

There are a few other details unique to police vehicles, too. One is the run lock ignition. At a crime scene, the officer may want to leave the car running for an extended period of time so the lights and radio can stay on without draining the battery. Run lock allows the engine to run without the key being in the ignition. If someone tries to steal the car, the run lock system cuts the engine when the parking brake is disengaged [source: Emergency Vehicle Solutions].

The interior lights in a police car can switch from typical white lighting to red lighting. Red lights don't affect your night vision as much, so during a nighttime traffic stop an officer can use the red light to read a driver's license or other paperwork. Then when the officer leaves the car, he or she won't be suddenly blinded by darkness.

Up next, we'll take a look at the history of police cars.

The History of Police Cars

­Police forces began using motorized vehicles sporadically as far back as the final years of the 19th century, but at the time, these were little more than wagons that carried police from place to place. Police forces used motorcycles on a regular basis long before they used cars, as cars were more expensive. Increased reliance on police cars was driven primarily by increased use of cars by criminals.

In the 1920s and '30s, police departments used police cars to save money. With a car and a radio, one officer could cover a much larger territory. During this period, cars were purchased retail and then modified by the police department. Modifications were limited -- rudimentary markings and a variety of lights were the only things that set most early police cars apart from regular cars. It wasn't until after World War II that U.S. auto companies began offering "police packages." They simply took the special options most often ordered by police departments and combined them into a special option package. Ford Motor Company debuted its police package in 1950; Chevrolet in 1955 and Dodge in 1956 [source: Sanow].

Over the decades, police cars have gradually evolved. More pieces of specialized equipment were added. Light bars were streamlined. Old cars went out of style, while new designs became popular. Here are just some of the key police cars through history:

If you're looking for more information about police cars or other related topics, follow the links on the next page.

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More Great Links


  • American Power Systems, Inc. "Heavy Duty PCM/RVC Smart Charge controlled alternators for Police Interceptor and Ambulance." (March 24, 2009)
  • Biggs, Henry. "Revealed: 211mph Police Lamborghini." Nov. 2, 2006. (March 24, 2009)
  • Emergency Vehicle Solutions. "Run Lock Relay Unit." Aug. 2, 2006. (March 24, 2009)
  • Hiltunen, Nick. "Suspect kicks out windows of police car." Goldsboro News-Argus. Feb. 17, 2008. (March 24, 2009)
  • Jones, Amy. "Hoover unveils Porsche as new police vehicle." Shelby County Reporter. Feb. 20, 2009. (March 24, 2009)
  • Kerr, Ian. "Police Cars." Chartwell Books.1998.
  • ­McCord, Monty. "Cars of the State Police and Highway Patrol." Krause Publication. 1994.
  • ­Sanow, Edwin J. "Chevrolet Police Cars." Krause Publications. 1997.
  • Sanow, Edwin J. "Ford Police Cars." Motorbooks International. 1997.
  • ­Shapiro, Larry. "Special Police Vehicles." MBI Publishing. 1999.