Contrary to public perception, there are few outstanding differences between the Police Interceptor and standard civilian Crown Victorias. By and large, the Police Interceptor uses the same Ford 4.6L 2V SOHC V8 Ford Modular engine and 4-speed automatic overdrive transmission as the civilian models. The Police Interceptor is equipped with an external oil-to-coolant heat exchanger to help reduce engine oil temperatures to help the vehicles idle for extended lengths of time without overheating. The engine oil coolers are notorious for seeping oil from the o-ring seals after extensive use.
The Police Interceptor also comes with a unique 140 MPH speedometer. The 2006-present Police Interceptors equipped with a 3.55:1 rear axle ratio from the factory are electronically limited to 120 MPH due to the lower driveline critical vehicle speed with the 3.55:1 rear axle ratio, while the Police Interceptors equipped with a 3.27:1 rear axle ratio have generally been limited to approximately 130 MPH. Ford used an aluminum metal matrix composite driveshaft for the 1999-early 2001 Police Interceptors as a measure to allow safe operation at over 130 MPH, but it was more expensive than the regular aluminum driveshafts. Ford eventually re-introduced the 3.55:1 rear axle ratio in the 2006 model year Police Interceptors, and set the speed limiter at 120 MPH to reduce the risk of driveline failure.
Another difference is Ford's "severe duty" shock absorbers that offer a stiffer ride than the civilian Crown Victoria. They also have black steel wheels with stainless steel or chromed plastic hubcaps.
Police Interceptors will have the characters "P71" as the model code in the VIN, instead of P70 (Stretched wheelbase), P72 (Commercial Heavy Duty / Taxi), P73 (Base), P74 (LX), or P75 (1992 Touring Sedan).
Features that are unique to the Police Interceptor engine calibration are a slightly higher idle speed (approximately 40 RPM higher) and minor changes in the emissions settings. Police Interceptors also have a reinforced frame and body mounts, an aluminum driveshaft (aluminum metal matrix composite for the 1999-early 2001 model years) and an optional limited slip rear differential. The front seats have a steel "stab plate" built into the back so that a suspect being transported in the back seat cannot stab the officers in the front seat with a knife or other sharp object. All Police Interceptors also come with T-409 stainless steel dual exhaust systems (without resonators); standard Crown Victorias come with a T-409 stainless steel single exhaust system while the Handling and Performance Package and LX Sport equipped Crown Victorias have the same T-409 stainless steel dual exhaust system as the Police Interceptor (with the resonators). The resonators further reduce noise, vibration, and harshness without adding any restriction to the exhaust system. Police Interceptors have higher rate coil springs, approximately 0.8 inches of additional ground clearance, and have thinner rear anti-roll bars than the LX Sport or Handling and Performance Package Crown Victorias; the base Crown Victoria does not have a rear anti-roll bar. Also, most Police Interceptors have a break in the front "bench seat" despite having the shifter on the steering column. This gap between seats is generally filled by a console holding radios, controls for emergency equipment, and often a laptop computer used as a mobile data terminal (MDT).
On 2004 and newer models, P71's have a 200 amp (A) alternator and a 78 ampere-hour (Ah) battery.
Ford also offers trunk packages for equipment storage (see below), and as of 2005, has added a fire suppression system to the Police Interceptor.
The bulk of police car modifications, such as installation of emergency lights, sirens, passenger seat dividers and plastic rear bench seats are offered as aftermarket modifications by third parties.