Bad A$$ Cop Cars
The latest Chevrolet Impala pursuit-rated Impala finally has the power to outrun a Crown Victoria Police Interceptor.
Sitting in my driveway is a Ford Special Service Package 4WD Expedition. (Special Service Package denotes a police vehicle that's intended for police duty but not designed for pursuits.) This one's equipped with a ProCharger D1SC-supercharged 5.4-liter engine that develops 370 hp and 465 lb ft at the flywheel. It sits 3.5 inches lower than stock, the result of a new suspension I developed that nearly eliminates body roll and understeer while vastly improving the handling. Drive into a gas station and I get curious glances from car-savvy guys who notice the tell-tale whine of the centrifugal blower. Occasionally one walks over, checks out the engine. "Sweeeeet. Bet this thing rocks. Too bad only cops can get the blower motor."
Actually, police don't get the trick engine either. People are always surprised to learn that, same as with other police vehicles, the cop-version Ford Expedition's powertrain is identical to the retail version. In fact, the only difference between them is the base police vehicle comes without a front console, floor mats or fog lamps (they're optional) and the floor and seats are covered in vinyl rather than carpet. (It's nice to be able to hose out the interior after transporting a messy drunk.)
According to urban legend, police cars have special high-output engines, giving them far better performance than their civilian counterparts. This was certainly the case at once time. Beginning in the mid-Fifties, the Big Three all offered "police packages", cars built specifically for law enforcement use. Ford and Chevrolet have continued their police-car programs continuously ever since. Chrysler, now Daimler-Chrysler or DCX, left following the 1990 model year as they battled nearly overwhelming financial woes. Theirs would be a 13-year absence, leaving the market to Ford and Chevrolet.
A few foreigner makes have taken a shot at filling that void. Volvo shopped around their four-cylinder turbocharged S70 sedan and V70 station wagon a few years back and both cars turned in stellar performance numbers. At least they did once Volvo engineers figured out how to prepare the cars.
At their debut at the prestigious Michigan State Police annual vehicle tests, in the acceleration and top speed tests the cars were a huge disappointment, performing well below expectations. It wasn't until much later that the problem was isolated. There were two factors. One, the cars' powertrain computers used fuzzy-logic algorithms to monitor engine speed, road speed, throttle position and a host of other parameters, helping them adapt engine and transmission parameters to driving style.
The second, related problem was the way the cars were delivered to Michigan. As it turned out, rather than being shipped by transporter, the cars were driven to the venue by employees of a press-fleet management company. These outfits maintain press fleets-vehicles delivered to the media for testing and evaluation-and many of their drivers are older part-timers, retired folks just trying to keep busy. Their driving is typically, well, very conservative. After the leisurely freeway cruise out from New Jersey, the Volvo PCMs were also, well, very relaxed. On the test track, they performed like they were being driven by an 80-year-old grandmother.
But even with very good numbers being turned in at the subsequent year's test, the Volvos were lousy candidates for police work. Retaining the console-mounted shifter, for instance, was a huge blunder. It made this critical area off-limits to the laptops, mobile data terminals and racks of controllers for emergency lights, sirens and other equipment that always-and I mean always-are floor- or console-mounted. (Chrysler wisely deleted the console and engineered a column shifter for its police Charger and Magnum.)
It didn't help that the Volvos were also too cramped, too expensive and front-wheel drive. Far worse, they weren't made in America. Cops don't like FWD cars and they like foreign police cars even less. Sure, Saabs have been used for years by police in the ski resort towns of Aspen and Vail, Colorado, plus a few other boutique departments. But with Aspen's substantial tax base (the median home price is well over $1 million and I don't know a single Aspen PD officer who's able to afford a home there) these affluent departments could easily afford the import's higher price, even without the sweetheart leasing deal given them by Saab in exchange for the publicity value.
Police cars look like their retail counterparts but underneath they are quite different. The frame is made of heavier-gauge high-strength steel with additional gussets, welds and braces. A skid plate protects engine vitals, allowing limited off-road capability. The body usually gets shock-tower braces or similar reinforcements to further stiffen the body. Brakes have larger rotors with different calipers and more fade-resistant pad materials. Cooling systems receive bigger radiators, heavy-duty fans, burst-resistant silicone hoses and even special heavy-duty aircraft-style hose clamps. There are fluid coolers for engine, transmission and power steering pump. Even the wheels are different.
When I owned a '90 Special Service Package Mustang, for example, I decided to do a tire test for one of the police magazines I write for. This called for spare wheels. That's when I discovered that although the police car's wheels appeared to be stock GT items, they weren't. Ford PR guys put me in touch with Bill Stroppe's operation near Los Angeles which at the time did much of the R&D for Ford police vehicles. A Stroppe engineer verified that yep, they looked similar to the stockers but nope, they weren't the same. The police wheels, it turned out, were thicker castings than the retail car's alloys. Police cars are routinely driven over curbs and through highway medians. Knowing this, the manufacturers design wheels accordingly. Steel wheels receive extra holes or slots for brake cooling and are also of thicker metal.
Suspensions are improved with higher-rate springs or torsion bars, bigger shock absorbers with firmer valving, more-robust bushings and ball joints; heavier anti-roll bars and a host of other upgrades. Until the early Nineties Ford even had a special quick-ratio steering box for its full-size police cars.
Engines have always been different too. Even the standard engines, generally V-8s rated anywhere from 250 to 375 gross hp depending upon the application, got heavy-duty valvetrains and thick-wall exhaust manifolds. GM and Ford even offered optional dual-carburetor big-block V-8s with high-lift, long-duration cams, high-compression pistons and low-restriction exhausts. In the case of Ford, many of these Sixties-era powerplants were called Police Interceptors, a name Ford resurrected only recently for the police Crown Victoria model.
From the beginning, modifications to police cars included upgraded cooling systems, bigger batteries and larger alternators. Brakes were improved with larger, better-ventilated drums, better linings and larger wheel cylinders but until the early Seventies, many vehicles wore drum brakes at all four corners. Their stopping distances were little better than the retail cars, but most could take more abuse before brake fade set in. But it wasn't until front disc brakes became common in the Seventies that the braking issue truly began to be remedied.
Transmissions received upgraded internals, external fluid coolers and modified linkages with first-gear lockouts to prevent over-revving. Rear-end gear ratios typically were numerically lower for better acceleration.
The mainline full-size police sedan of the period, unless it was packing one of the optional high-output engines, was good for around 125 mph. That varied considerably depending upon the amount of drag-inducing gear carried externally, overhead lights in particular, which were gradually evolving from single or dual rotating, multi-beam circular lights to clunky, square light bars.
The high-water mark of the police sedan came in the late Sixties. This coincided with the peak of the muscle car era and all the manufacturers were already producing mid-size and full-size cars packing engines with displacements up to and beyond 7 liters. Dodge and Plymouth offered 383 and 440 cubic-inchers rated up to 375 hp. Ford had a Police Interceptor version of its 406-, 427 and 428-cubic-inch engines. Likewise, police Chevrolet Impalas were available with 396 and even 427 cubic-inch engines.
Probably the best known police Mopars of the era were the full-size Dodge Polara and Plymouth Fury I sedans, both built on the same platform and almost identical save for bodywork. City departments favored the 330 hp 383-cubic-incher; highway patrols preferred the 440 engine rated at 360 hp or, with a more radical camshaft, 375 hp. With a 3.23 axle ratio they could run 0-60 mph in the low six-second region and cover the quarter mile in 14 seconds at 99 mph. Healthy specimens were timed at 147 mph; a factory car reached 149.7 mph at Chrysler's Chelsea, Michigan proving grounds, a top-speed record for police cars that stood for nearly 25 years until it was broken by the B4C police-package Camaro.
By 1971 increasingly stringent emissions regulations had started emasculating engines, making it impossible to justify the cost of developing and certifying higher-output versions strictly for the police-car market. (There are fewer than 500,000 of them in service nationwide with only about 60,000 new cars are sold annually.) The 440-inch Mopar V-8, by this time producing a feeble 245 hp, became history after the 1978 model year. A 400-inch smog engine lingered briefly as the top engine choice. When it was phased out a 360-CID engine became the top dog. By 1989 Chrysler's police-car offerings were limited to the Dodge Diplomat and Plymouth Fury powered by a 318 cubic-inch engine rated at 155 hp.
Ford's array of full-size police car engines had wasted away to only one by that time: the 351 Windsor with its fiendishly complex and notoriously unreliable variable-venturi two-barrel carburetor. Horsepower: 152. Chevrolet soldiered on with the Caprice, available with a 175 hp 305-inch or 205 hp 350-inch engine. The Ford and Chrysler could reach about 105 mph, the Chevrolet as much as 115 mph.
From that point on, police cars would carry the same engines as retail cars, modified for durability but offering little more performance.
Some examples: The 4.6-liter Triton engine powering the police 2007 Crown Victoria is rated at 250 hp and 297 lb-ft. The civilian version with dual exhausts has 239 hp and 287 lb-ft. The extra 11 hp of the police version is derived from a wide-open throttle A/C cutoff and minor software tweaks to the powertrain computer. The Chevrolet 9C1 Impala's 3.9-liter V-6 is rated at 240 hp and 245 lb ft. The civilian version: 233 hp and 240 lb ft. The Chevy also has a WOT A/C cutoff feature and revised PCM. The police Dodge Charger V-6 pumps out 250 hp and 250 lb ft. The 2007-model 5.7 Hemi version is good for 340 hp and 390 lb ft. Both engines produce exactly the same power as their retail counterparts.
The main differences in today's police-car engines continue to be those made to the frame, body, suspension, engine and brakes to enhance durability. But none of these upgrades makes the car any faster. In fact, they usually make it slower. Once fully equipped, the typical police car is up to 400 pounds heavier than a similarly optioned retail car. Most of the added heft comes from a light bar (20-60 pounds), auxiliary emergency lights (10-25 pounds), push bumpers (35-65 pounds), siren (6-10 pounds), 2 to 3 radios with antennas (10-15 pounds), control units for siren and lights plus extra wiring and fuse panels (10 pounds); mobile video recording system (35 pounds), prisoner partition (110 pounds), heavy-duty chassis, skid plates and other police-spec enhancements (100 pounds). All this takes a toll on acceleration.
And when aerodynamics are compromised by the light bar, spotlights, push bumpers, external sirens and other drag-inducing gear, the police car often has a lower top speed to boot. That's one of the reasons a percentage of most highway patrol fleets is composed of slick-tops-units without light bars- sometimes without spotlights and pushbars as well.
Aerodynamic drag can exact a surprising penalty in top-end performance. For example, in 1999 when I tested the new FWD Chevrolet Impala 9C1 police car (Chevy's model designation for the pursuit-rated sedan), it struggled to reach 113 mph and took two miles to achieve that. During track testing it understeered so badly that the right-front tire ground itself into rubber dust and I had to swap it for the spare after a few dozen hot laps. Worse, my Ford Expedition, then unmodified and producing 260 hp, easily out-accelerated the Chevy coming out of slow, second-gear corners.
The feeble top speed was largely attributable to the test car's Wheelen strobe light bar whose flat face added nearly two square feet of frontal area to the car, acting just like an air brake. A few years earlier I'd tested two identical 1995 Chevrolet B4C police Camaros. The slick-top car hit 153 mph. The other, equipped with the same Whelen light bar as the Impala, was maxed-out at only 136 mph. And these were 275 hp, 3400-pound cars with excellent Cd (coefficient of drag) numbers. The Impala weighed more, had more frontal area and thus more drag, and its wheezy old 3.8-liter V-6 generated 200 hp. Burdened with that boxy light bar, the meager top speed was hardly a shock. Without the light bar, spotlights and push bumpers, the same car could hit 124 mph.
The Impala's leisurely acceleration exiting those slow second-gear corners could have been overcome if I could have manually downshifted to first. But police cars have first-gear lockouts to prevent overenthusiastic officers from manually grabbing first and over-revving the engine. Chevy's is unusually intrusive. Once the transmission shifts into second, the powertrain computer won't make first gear available again until the vehicle has nearly stopped.
For model year 2006 Chevy finally axed the ancient 3.8-liter in favor of the more sophisticated 3.9-liter V-6. It's still a two-valve pushrod motor, but variable valve timing amps up the power to 240 hp, enough to significantly improve acceleration and top speed.
When the Camaro was offered as a police car it was almost identical to the retail car and remained so until production ceased in 2002. Chevrolet Police Vehicle program manager Bob Hapiak loaned me one of his 1994-model engineering cars for a year, after which I purchased it. The B4C package, GM nomenclature for the Special Service Package Camaro, had the same 275 hp 5.7-liter LT1 small block and its six-speed manual was linked to the same 3.42 final drive found in the retail car. The only difference was its larger alternator.
Don't look for a return any time soon to the glory days of police cars in the Sixties and early Seventies. Once the specter of emissions and safety regulations descended like a pall over the industry, the notion of special-purpose powertrains for cop cars became a thing of the past.
The latest Chevrolet Impala pursuit-rated Impala finally has the power to outrun a Crown Victoria Police Interceptor.
The police Celebrity proved too fragile for police work and its anemic 2.8-liter V-6 had barely enough power to induce wheelspin on glare ice
The LX-platform siblings are excellent police cars. When Hemi-equipped, top speed is limited to 146 mph. But they're much faster.
In partnership with Police Magazine, I constructed the most elaborately equipped traffic-enforcement Camaro ever. Gear included radar, laser, time/distance computer, video system and enough emergency lights to illuminate downtown Minneapolis. It was far superior to the Mustang in every way.
1995 9C1 Caprice, the best all-around cop car ever built. Great brakes and handling, good acceleration, anvil-like reliability and 140 mph-plus top end.
Tahoe 2WD is pursuit-rated, accelerates and stops as well as the Ford Crown Victoria Police Interceptor. Handling is impressive for a 2.5-ton truck. I reached its governed 124 mph top speed even at a power-sapping 7,000 feet of altitude in New Mexico.
2007 P71-code Crown Victoria Police Interceptor is the best Ford police sedan in decades. But its 4.6-liter's power output is nearly identical to the retail car's.
My 1989 five-speed 5.0-liter Mustang Special Service Package could reach 144 mph. But its fade-prone brakes and twitchy handling made it a handful to drive at the limit.
