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What a police package actually buys
Two Chevrolet Tahoes, same platform, same engine, tested on the same day. Across their first six stops they averaged a quarter of a foot apart. After a heat soak, one of them needed twenty feet more.
Ask what makes a police car a police car and you will get a list: heavier springs, bigger brakes, a calibrated speedometer, an alternator that can carry the load, seats without a centre console. All true, all verifiable from an order guide, and none of it tells you what difference any of it makes.
The Michigan tests answer that question, but not in the place you would look. It is not in the 0–60 times, where a police package and a civilian one are often close. It is in a single pass-or-fail line on the brake sheet, and it took four years of reading them in order before the pattern became undeniable.
The question nobody notices
Michigan’s braking procedure is a run of stops, not one. From 1999 it ran twelve measured stops from 60 mph in two phases of six, each preceded by two heat-up stops from 90 mph, with a four-minute heat soak between the phases; from the 2012 book it became twenty, in two sets of ten with a cool-down drive between them. The point is not the first stop. Anything stops well once. The score is, in most books, the average over the whole run.
At the bottom of every vehicle’s sheet is a question with a one-word answer: evidence of severe fading?
Almost every vehicle in fifty years of these books answers no. It is the least interesting column on the page — until you notice which vehicles answer yes.
Two Tahoes, four years
In 2005 Michigan tested the Tahoe in two forms: a police package PPV, listed in the police category, and a special service four-wheel-drive version, tested as special service every year since 2001, which Michigan places in a separate section headed with a warning that such vehicles are not engineered for high-speed or pursuit driving.
Same platform. Same 5.3-litre V8 in the car that was tested. Same day, same proving ground, same procedure. The 2005 brake sheets read like this:
| Chevrolet Tahoe | Phase I | Phase I rate | Phase II | Phase II rate | Fade? |
|---|---|---|---|---|---|
| Police package PPV (2WD) | 144.87 ft | 26.88 ft/s² | 145.15 ft | 26.86 ft/s² | No |
| Special service (4WD) | 144.65 ft | 26.67 ft/s² | 164.62 ft | 23.90 ft/s² | Yes |
Read the Phase I figures and the two vehicles are all but level. The special-service car’s six stops average a quarter of a foot shorter, though its printed rate is slightly lower, and on the very first stop it needed 149.2 feet to the police car’s 144.6. A buyer taking one round the block would find little to choose between them.
Then the brakes get hot. The police package car’s average stop grows by three tenths of a foot. The special-service car’s grows by twenty feet, and its last stop took 185.7 feet against the police car’s 151.0.
The difference between the two packages is small across the first six stops and large by the last. That is the situation the designation exists to describe.
One result is an anecdote. This one repeated. The special-service four-wheel-drive Tahoe answered yes to the fading question again in 2007 — where it was the only vehicle in the entire test to do so — and again in 2008, where it needed 173.7 feet, the longest stop of any four-wheeled vehicle in that year’s field.
Across the same three years, the police-package PPV built on the same platform never faded once.
What that twenty feet is
Fade is not a number the buyer ever sees. It is what happens when the friction material and the fluid get hot enough that the same pedal pressure produces less retardation — and it arrives suddenly, several stops into a sequence, at exactly the moment nobody is thinking about brake temperature.
Twenty feet is not a rounding error. On Michigan’s own scored measure, the projected stop from 60 mph, the two Tahoes ended 9.0 feet apart (144.1 against 153.1); in the same test the police-package vehicles’ projected stops spanned 11.5 feet, from the Impala’s 136.3 to the 3.55 Police Interceptor’s 147.8.
This is what the fading question is for. Not the paint, not the speedometer, not the vinyl seats: it tests what happens on the twelfth stop rather than the first. The reports record the result, not the cause; they do not say which part of either Tahoe made the difference, and the two 2005 Tahoes also differed in drivetrain and weight (5,341 against 5,034 pounds).
The designation is the manufacturer’s, not Michigan’s
It matters that Michigan did not invent this split. Package and special service are the manufacturer’s designations, declared when the vehicle is submitted. What Michigan does is test them and print the results.
The programme formalised the distinction in 1999, saying that vehicles able to perform “a variety of police functions, up to and including participating in a pursuit” have “earned the right to be called Police-Package vehicles”, and moving the special-service vehicles into an appendix. Special-service vehicles were already in the books before that; the 1999 book is the first held here to give them an appendix of their own. The year before is instructive. In 1998 the Expedition and both Explorers did not run the road course at all: Ford had advised that they were not designed or intended for pursuit. The federal bulletin printed that note, and the next book divides its field along the same line.
And the department is careful about the limits of its own authority. As the 2019 book states plainly, there is no sanctioning body behind the phrase “pursuit rated” and neither Michigan nor the Los Angeles County Sheriff’s Department can award it. What the manufacturer can do is declare a package — and then live with the brake sheet.
The other way it shows up
Fade is the cleanest evidence, but not the only kind. Two more examples from the same archive, both involving Tahoes, both showing the same thing from different angles.
In 2015 a four-wheel-drive Tahoe was listed in the police category, a first in the books held here — and then left the track during the dynamics test. Two drivers’ laps from that day are printed; General Motors traced the incident to a temporary brake torque output difference, and the book prints the retest of 23 October, at 1:39.64, rather than quietly dropping the vehicle.
And in 2019, both Tahoes in the test went into partial power or protect mode on lap seven or eight of every run, for every driver, in temperatures reaching 88°F. General Motors engineers believed the cause was the thermal bypass valves that control transmission oil cooling; with them replaced, one car lost power again. The Los Angeles County Sheriff’s Department tested both and the four-wheel-drive car overheated once more. It was redeveloped and completed all 32 laps of LASD’s course in January 2019, and Michigan accepted that result.
Again: none of that appears in a 0–60 time or a top speed. It appears in durability, under repetition, in heat — which is the only condition that matters and the only one a spec sheet cannot describe.
A police package is not a performance option. It is a promise about the tenth repetition, and Michigan is one of the very few places that ever checks.
What this means if you own one
If you have a special-service vehicle, you have a good truck that was never meant to be driven like a patrol car. That is not a criticism: a 2005 special-service Tahoe’s first six stops averaged a quarter of a foot shorter than the police car’s. It means the margin is thinner than the first stops suggest, and it disappears under repetition.
If you are buying, the package code is the fact and the phrase is not. Ask for the code — 9C1, P71, PPV, and the rest — and check it against the build sheet rather than the advertisement. Our guide to identifying a genuine police package car covers where to look, and the option codes reference lists the codes themselves.
And whatever you own, replace the brake fluid. Every one of those twenty-foot results is a story about heat, and fluid that has absorbed moisture over twenty years fades long before any pad does. It is the cheapest thing on this page and the only one you can fix in an afternoon.