with Police Magazine
Performance Review: Police cars
by John L. Bellah
No one other than a patrol officer is better able to understand the vital role of a police vehicle in today's law enforcement. The wrong vehicle can affect officer morale, reduce efficiency and increase a department's operating costs appreciably.
Each year two agencies - the Michigan State Police and the Los Angeles County Sheriff's Department - test and evaluate police cars with a degree of thoroughness and accuracy that makes them the authorities on police vehicle performance.
This Police magazine report is primarily based on testing performed late last year by the Los Angeles County Sheriff's Department. The LASD Law Enforcement Vehicle Test and Evaluation Program, in addition to measuring vehicle performance, also utilizes test procedures to predict long-range vehicle reliability factors and other concerns that affect the vehicle purchase decisions of law enforcement agencies.
For example, to help determine long-range engine and component reliability, various measurements including the temperatures of engine oil, coolant, transmission fluid and power steering fluid are recorded under conditions that simulate patrol car duty on a hot summer day.
Kicking the Tires
LASD mechanics also evaluated each vehicle and rendered judgments on ease and cost of maintenance and repair. These evaluations took into account transmission or water pump replacement, as well as oil and filter changes and tune-ups.
And some non-mechanical issues were considered.
Technicians studied the difficulty of installing the emergency equipment - prisoner cages, shotgun racks, radios, sirens, and warning lights - and noted less than obvious factors such as the excessive radio interference some of this equipment can cause.
Ergonomics is one of the most important concerns for the patrol officers who have to ride in these cars, and the LASD testing accounts for the interior design of the vehicles. For example the evaluation team notes when the awkward placement of a control device could contribute to the cause of an accident. Beyond safety and convenience, these officers also rated the cars on comfort, knowing full well an uncomfortable vehicle will seriously affect morale over a more than 8-hour tour of duty.
Rules of the Road
For the 2002 model year LASD tests, the vehicles were divided into two categories, pursuit class and special service. Each vehicle was required to complete the "Preliminary Handling and Test Driver's Subjective Evaluation."
During this phase of testing, each driver completed eight laps around a 1.57-mile test track laid out in the parking lot of the Los Angeles County Fairplex in Pomona, California. This high-speed driving course consists of three straight stretches and three braking areas. Each car ran a total of 32 laps, and vehicles judged "unacceptable" were disqualified from further testing.
After the prelim, which is a good simulation of pursuit conditions, the brakes were tested. The drivers accelerated the vehicles to a speed of 90 mph, then applied the brakes. The goal was to maintain a 22-feet-per-second deceleration rate.
The deceleration rate test was repeated twice, and each vehicle was allowed to cool down for five minutes. Then each vehicle was accelerated to 60 mph, and the brakes were applied - just short of the ABS feature becoming active. This was repeated twice, and followed by a 60-mph panic stop (with ABS).
If any correctable failures were noted during the braking and deceleration tests, the vehicle was repaired and retested. If the failures appeared to be an engineering defect, the vehicle was disqualified.
The LASD does not record top speeds. However, the elapsed time and speed to complete each lap was measured, as well as the acceleration time to various speeds, including 0 to 100 mph.
Pursuit class vehicles receive a second evaluation on a "Pursuit Course." This course covers 2.45 miles, simulating a pursuit in an urban area. There are no straight-aways, and various obstacles are intermixed with various right and left turns. The Pursuit Course is also utilized in the tire tests, which include tires from several manufacturers.
Fuel mileage was checked by driving a predetermined 100-mile course. The course covers urban, suburban and freeway driving conditions, during which the cars were driven normally. Headlamps, radios, and air-conditioning systems were operated, simulating the mileage that a detective unit would tally under average usage. (As a point of reference, a marked unit's mileage is typically about 60 percent of this figure, due to the nature of its assignment - idling, low-speed, patrol, and emergency responses.)
The LASD clearly states in its literature that different agencies have different needs. Its program does not recommend any particular make or model of vehicle. To obtain any additional information or to obtain copies of the complete test results contact:
Los Angeles County Sheriff's Department Fleet Management Unit
1104 N. Eastern Avenue Door #50
Los Angeles, California 90063
Makes and Models
CHEVROLET: Front-wheel-drive (fwd) vehicles have been slow to gain acceptance in the police market. However, Chevrolet engineers designed the fwd Impala from the ground-up as a police car. In this case, the civilian versions are also fitted with standard components that were designed for police duty.
Many fwd vehicles are disabled after seemingly minor front-end collisions. Chevrolet engineers designed an engine cradle for the Impala that will survive striking a 6-inch curb at a speed of 25 mph, with only damage to the tires and/or wheels.
The Impala is powered by a 3.8-liter V-6 engine that develops 200 horsepower. And although it weighs about 300 pounds less than Ford's Crown Victoria, the Chevy's performance was noticeably slower than the Ford. Zero-to-60 times are slightly more than one-half-second slower than the Crown Victoria, and in 0- to 100-mph runs the Impala is slower by one and a half-seconds.
But speed isn't everything in a police car. And a huge vote of confidence has been given to the Impala by the New York City Police Department.
Based on two years of dependable service, it has been reported that NYPD plans to eventually convert its entire patrol fleet to Impalas. The on-duty Chevys have received high marks for durable engines, transmissions, and brakes.
However, the word on the Impala is not all good. There have been reports of some frame members cracking. To address this concern, Chevrolet is changing the alloy of the affected frame members. Additionally a running production change will be made this year with the engine mounts and front springs to redistribute vertical road shocks.
This will be the final year for the Chevrolet B4C Special Service Package Camaro. Both Camaro and Pontiac Firebird are being phased out by General Motors. The police package Camaro is powered by the 310-horsepower 5.7-liter V-8. The transmission is a 4-speed automatic.
The Chevrolet Tahoe, a super-sized sport utility vehicle, is available in a Special Service Package in both 2-wheel-drive and 4-wheel-drive versions. Chevrolet is considering a pursuit-capable Tahoe, and a prototype was brought to Pomona for evaluation.
Currently, the only pursuit-capable sport utility vehicle is GM's Hummer 4-door wagon HCMS Tactical Vehicle - TPU. The high-end TPU is powered by a 6.5-liter turbodiesel developing 195 horsepower and a whopping 430 foot/pounds of torque. The 4L80-E 4-speed automatic is the only available transmission. According to the manufacturer, numerous options and paint schemes are available.
Chevrolet also offers a 1SA Package for its full-sized van. Referred to as a Special Service Package, and intended for prisoner transport, the Chevy van can carry up to 15 persons and is available with a 5.7-liter gasoline V-8 or a 6.5-liter turbo diesel.
DODGE: Dodge is attempting a comeback into the police market with a police package version of its Intrepid. In recent years, many agencies fell in love with this vehicle and have purchased standard, retail Intrepids with heavy-duty options, placing them into service as marked police units.
The DaimlerChrysler folks have taken notice, and spurred by the success of Chevrolet's Impala Dodge has introduced a special police package Intrepid for the 2002 model year.
The Intrepid is a fwd car powered by a 3.5-liter V-6 engine that develops 242 horsepower. And based on the LASD evaluation, it offers better handling and ease of repair than its primary fwd police vehicle competitor, the Chevy Impala.
Dodge, like Chevrolet, also is engineering extra protection against powertrain abuse into its police vehicle models. At Pomona, a test Intrepid slammed into a 6-inch curb at a speed of 25 mph, and drove away needing nothing more serious or costly than a front-end realignment.
A prototype Intrepid scorched the track of the Michigan State Police tests at 135 mph, where top speeds are recorded. Unfortunately, the Intrepid did not pass MSP's braking standards. To correct this problem Dodge made some changes to the brake system by adding some cooling slots, and changing the friction materials. During the LASD testing, the Intrepid demonstrated blistering performance, turning in some lap times in the 1-minute-and-23-second range - faster than the Impala and Crown Victoria.
However, during Lap 31 of the 32-lap preliminary handling evaluation, the Intrepid developed severe brake fade, and the manufacturer voluntarily withdrew it from testing. Gerry Appie, DaimlerChrysler's manager of fleet engineering, said the Intrepid is tentatively scheduled for a retest later this month.
FORD: The 2002 Ford Crown Victoria was redesigned to improve engine cooling and electrical charging at idle speeds. In addition, suspension ball-joints have been improved for added durability, and the fuel systems on the Natural Gas Vehicles (NGV) have been reengineered for increased luggage space and increased range between fuelings.
Major changes are slated for the 2003 Crown Victoria. Most of the modifications, including rack-and-pinion steering and stronger suspension components, are intended to improve handling and durability. Rear shock absorbers will be relocated for better handling. Frame rails will be hydro-formed to eliminate structural weaknesses.
Ford SUVs, including Explorer, Expedition and Excursion, have also attracted attention from some agencies. These special service vehicles are available in 2-wheel-drive and 4-wheel-drive versions, but they are not pursuit-capable vehicles.
John L. Bellah currently holds the rank of corporal with the California State University, Long Beach Police Department. He is a frequent contributor to numerous publications, including POLICE.