Each year since the 1978 models, nearly 30 years, the Michigan State Police has tested a variety of police package (pursuit capable) and special service package (not intended for pursuit) patrol vehicles. These annual tests include acceleration to 100 mph, absolute top speed, braking from 60 mph after brake warm-up, road racing course lap times, an ergonomic and communications installation review, and EPA fuel economy ratings.
The acceleration, top speed and braking phases are conducted at Chrysler’s Proving Grounds near Chelsea, MI. The vehicle dynamics testing are performed on the 2.0-mile road course at Grattan Raceway near Grand Rapids, MI.
For the 2007 models, the MSP tested five police package sedans, nine SUVs and specialty vehicles, and a special service package pickup truck. The special service package and the police package vehicles are tested alike with one exception. Because the special service package vehicles are not designed for, nor intended for, emergency or pursuit driving, these vehicles are not run on the road course. Only the pursuit-capable vehicles, as identified by the respective carmakers, undergo the high-speed, vehicle dynamics testing.
New for 2007
The police package sedans included the 4.6L V-8 RWD Ford Crown Victoria Police Interceptor (CVPI) in both 3.27 and 3.55 rear gear ratios; the RWD Dodge Charger powered by both the 3.5L V-6 and the 5.7L V-8; and the 3.9L V-6 FWD Chevrolet Impala. The only police package, pursuit-rated SUV is the 5.3L V-8 2WD Chevrolet Tahoe, and the MSP tested both the gasoline-only and the E85 flex fuel versions.
The special service package SUVs included the 5.3L V-8 4x4 Chevrolet Tahoe, the 4.6L V-8 2WD Ford Explorer, the 5.4L V-8 2WD Ford Expedition, and the 5.4L V-8 2WD Ford Expedition EL, the new stretched version. The specialty vehicles included the RWD Dodge Magnum powered by both the 3.5L V-6 and the 5.7L V-8; the 5.4L V-8 4x4 Ford F-250 pickup and the 2.3L I-4 FWD Ford Escape Hybrid. Both the F-250 and the Escape Hybrid are new to the MSP tests.
Nearly all of the police and special service vehicles are carryover designs from 2006. In fact, just two vehicles have had significant changes, the Tahoe and the Expedition EL. The Tahoe underwent a redesign for 2007 than included new sheetmetal and suspension and powertrain upgrades. It has a V-8 engine with 25hp more.
The Expedition EL is a new vehicle, essentially a stretched version of the Expedition. The Expedition EL is the replacement for the discontinued Ford Excursion and a direct competitor to the Chevrolet Suburban, which was not tested by the MSP. More on both these vehicles in future issues.
The acceleration tests have maximum times allowed to reach 60 mph, 80 mph and 100 mph. The score for the event, however, is based on the zero-to-100-mph times. The tests are conducted slicktop, with no spotlights and with two troopers on board.
Of all the 2007 models, the fastest-accelerating vehicles were the two Hemi®-powered Dodges. The Charger 5.7L V-8 and the Magnum 5.7L V-8 both reached 60 mph in 6.5 seconds. The Hemi Charger sedan took just 16.3 seconds to reach 100 mph. In comparison, all the rest of the V-6 and V-8 sedans reached 100 mph in the 24-second bracket.
Whether or not it makes sense, the 3.55-geared Ford CVPI and the 3.27-geared Ford CVPI produced exactly the same acceleration. Both hit 60 mph in 8.7 seconds and 100 mph in 24.0 seconds. The 3.55-geared CVPI is speed limited to 119 mph, while the 3.27-geared car is opened up to 130 mph. Because the 3.27 gearing will almost certainly give better fuel economy than the same car with 3.55 gears, the option of a 3.55 gear ratio does not appear to have any advantages.
What effect does E85 ethanol have on vehicle performance? It improves it! Compared with the gasoline-powered, 2WD Tahoe, the E85-powered 2WD Tahoe was a tenth-second faster to 60 mph and a full second faster to 100 mph. The gasoline-powered Tahoe and the Ford CVPI have very similar performance, reaching 100 mph in 24.5 seconds and 24.0 seconds, respectively.
How does the acceleration compare among the V-6 Impala, the V-6 Charger and the V-8 Ford CVPI? The acceleration is just about the same, 8.8 seconds, 8.8 seconds and 8.7 seconds, respectively. And they hit 100 mph in 24.1 seconds, 24.1 seconds and 24.0 seconds, respectively. Virtually no acceleration difference whatsoever exists between these three sedans.
Among the special service package SUVs, the 4.6L V-8 Ford Explorer was the hot rod. It reached 60 mph in 8.8 seconds, just like most of the police sedans. The Explorer also reached 100 mph in the same 24-second bracket as most of the police sedans. The other special service package vehicles (Magnum, Expedition, 4x4 Tahoe, Expedition EL) all hit 60 mph between 8.8 and 9.8 seconds.
The two new vehicles, the Ford F-250 pickup and Ford Escape Hybrid, were run as a baseline to give departments some idea what to expect. The F-250 hit 60 mph in 10.3 seconds, while the Escape Hybrid took 12.8 seconds.
The second MSP test is top speed. At the end of the last acceleration run, the MSP troopers continue to accelerate the car around the 4.7-mile oval. The highest speed recorded anywhere on the course is the top speed of record. For one reason or another, all police and special service vehicles are electronically speed limited but not all vehicles actually reach that preset, limited speed.
Last year, the Hemi Charger broke the top speed record for a police sedan set in 1969. Those were the heady days of big block V-8s with massive carburetors and high-compression ratios. The fastest officially timed police sedan was the 1969 440ci Dodge Polara with a top speed of 147 mph on this same Chelsea Proving Ground oval. The 2006 5.7L Dodge Charger had a top speed of 150 mph flat. This year, it was back with a 148 mph top end. It is actually speed limited to around 147 mph.
All of the other police package sedans and SUVs, ran between 130 and 139 mph. The single exception is the 3.55-geared Ford CVPI, which is limited to 119 mph for reasons of driveshaft harmonics. The V-6 Impala reached 139 mph compared to the V-6 Charger at 132 mph and the Ford CVPI at 130 mph. At 136 mph (gas) and 137 mph (E85), the pursuit-rated Tahoe was a very serious competitor. It used to be limited to 124 mph.
The Ford F-250 was speed limited to 95 mph, and the Escape Hybrid reached 102 mph.
A side note on these top speed tests: The police department may not see the same top speeds from the in-service car as these cars achieve during testing. The fully-upfitted patrol car weighs much more than these cars as tested. The addition of spotlights and lightbars adds aerodynamic drag, and so does the addition of a front push bumper.
In some cases, depending on the extra weight and aerodynamic load, the car may or may not shift into the gear producing the most top speed, or may select a certain gear, hit the engine rpm limiter, and shut off without upshifting. If your department has a specific top speed the vehicle must reach, put it in the bid spec.
The MSP braking protocol involves two 90-mph, full-pedal stops to warm the brakes, followed by six 60-mph full-pedal stops for score. After a heat soak period, these two 90-mph and six 60-mph stops are repeated. The best 10 out of 12 stops from 60 mph are averaged for the final deceleration rate. This then is converted to a projected stopping distance from 60 mph.
The MSP has established a maximum stopping distance for its large patrol sedans, both RWD (Ford CVPI, Dodge Charger) and FWD (Impala). The standard is about the same at 149.7 feet and 149.1 feet, respectively.
Like last year, the V-6 and V-8 Charger and Magnum all stopped between 129.9 feet and 132.8 feet. Again, the V-6 Charger took the honors for the shortest stops from a four-door police sedan. Next was the V-6 Impala at 140.5 feet. The 3.27-geared and 3.55-geared CVPI were next with 142- and 143-foot stops.
The new Tahoe definitely has the brakes to go with the more powerful engine. This SUV stopped in 138.2 feet, shorter than the Impala and Ford CVPI sedans. All the rest of SUVs stopped from 60 mph in about 150 feet. The heaviest SUV of the test, the stretched Expedition EL, produced the shortest stops of all the other SUVs at 147.9 feet. The F-250 Crew Cab stopped in 155 feet, while the Escape Hybrid did it in 139 feet.
The Grattan Raceway is a 2-mile, 13-turn, road-racing course with a 3,200-foot front straightaway. By the end of the straight, the 250hp Ford CVPI, for example, reaches 110 mph. The course also has a number of twists and off-camber turns. On some parts of the track, the cars get nearly airborne while on other sections of track the suspension almost completely bottoms out. Each car is driven five laps by four different MSP troopers from the Precision Driving Unit.
On the road course, the fastest two police package vehicles were Hemi-powered—the Dodge Charger V-8 and the Dodge Magnum V-8. These vehicles were 3.3 seconds quicker than the next closest cars. With lap times of 1 minute, 40 seconds, the time interval between the Hemi Dodges and the other sedans works out to a 16 car-length difference.
The 3.55-gear Ford CVPI, the 3.27-geared Ford CVPI and the V-6 Charger were all clustered together in a pack well behind the Hemi Dodges. Less than a quarter-second separated these three sedans.
The 3.9L Chevy Impala was about 2 seconds, or 10 car-lengths behind this three-car pack, and the police package Tahoe 2WD was a second behind the new Impala. For the Tahoe, that is an impressive 2-second improvement over last year.
On the road course, the two Hemi-powered Dodges, and especially the 2WD Tahoe, showed some wheelspin. On the police cars, the DaimlerChrysler Electronic Stability Program (stability control) is tuned for more aggressive driving than the special service or retail cars. As such, the ESP allows a little more wheelspin, a little more understeer and a little more throttle-induced oversteer.
The Tahoe, however, is designed to allow wheelspin under heavy acceleration, which limits oversteer. That is why it is important to put the exact same OE tires back on the Tahoe. It is important for the overall handling not to change the amount of traction (either more or less) given by the tires. The 2WD Police Tahoe is not equipped with GM’s StabiliTrak stability control system.
The MSP does not test special service package vehicles, such as the Ford Explorer, Chevrolet Tahoe 4x4, Ford Expedition or Ford F-250 Crew Cab, on the road course. This is an emphasis that, in addition to clear and frequent written disclaimers from each manufacturer, these vehicles are not intended for high-speed, pursuit-style driving.
The Michigan State Police base their fuel economy rating on the EPA City mileage results. Fuel economy matters. Because fuel economy is a tangible cost, unlike acceleration to 100 mph, for example, some fleet managers consider this operating expense on equal footing with the initial expense of the vehicle. They are not going to spend $0.15/gallon difference for a car that runs on premium fuel. Yet selecting a patrol vehicle with a 1.7-mpg difference in mileage is (cost-wise) the same as selecting an engine that runs on premium.
The Ford CVPI, the V-8 powered Dodge Charger and Magnum are all rated at 17 mpg (EPA City). The Chevy Impala and the V-6 powered Charger and Magnum are all rated at 19 mpg (EPA City). The Tahoe in both 2WD and 4x4 is rated at 15 mpg (EPA City) while the 4.6L Explorer and 5.4L Expedition are both rated at 14 mpg (EPA City).
No police patrol vehicle ever gets EPA Highway mileage, and only the easiest-driven admin cars ever get EPA City mileage. Based on research conducted by the Illinois State Police, the patrol vehicles get between 70 and 75% of the EPA City rating. Expect 25 to 30% less mileage when running on E85 ethanol.
Fleet managers divide police cars into so many categories, it is extremely difficult to point to any one car as a “winner” based on the NIJ-funded MSP tests. Across the nation, fleet bid categories are subdivided into FWD and RWD, into V-6 and V-8, etc. The “winning” car, the car with the best overall performance may be the best V-6 powered sedan, or the best RWD sedan, or the best V-8 RWD sedan.
For its part, regardless of vehicle platform, the MSP is careful to point out that these tests (the minimums, the maximums and the category weights) are all designed for the way the MSP uses its patrol vehicles. Other departments will certainly use their vehicles in a different way, and this should put a different emphasis on the test results.
If some of the artificial bid distinctions are removed, and instead “police package sedan” is used, a winner in each vehicle performance category is obvious. The Charger V-8 has the fastest acceleration, the highest top speed, the quickest road course times and the shortest braking distances. In the shootout among the V-6 police sedans, the performance and fuel economy results were evenly split between the V-6 Impala and the V-6 Charger. And both of these were virtually identical to the Ford CVPI.
Weighing the Test Phases
The MSP weighs the six test phases to suit the needs of a state police or highway patrol. The needs of city and county law enforcement agencies probably are very different. While subtle changes have taken place from time to time, the MSP typically weighs the tests as road course: 30% acceleration: 20% braking: 20%, top speed: 15%, ergonomics: and 10% fuel economy: 5%. These numbers are plugged into a bid adjustment formula. This formula may be used by any agency and is available at the NLECTC Web site.
Different weightings may be selected. For example, an urban department may want to emphasize fuel economy, ergonomics and braking while deemphasizing road course, acceleration and top speed. Because most bids are close, this change in weighting may point to a different “most bang for the buck” police vehicle.