1999 Michigan State Police Patrol Vehicle Test

The Volvo sedan is the interesting shape here. It is slower off the line than the Police Interceptor to 60 mph — 8.86 against 8.55 — and then beats it to 100 by four full seconds. A turbocharged 2.3-liter Volvo with 236 horsepower against a 4.6-liter Ford with 215.

Four drivers — Sergeants Stevens, Clark, Rothermel and Pokora — ran each car over the 1.635-mile road course at Michigan International Speedway, sixteen timed laps per vehicle.

A note this data settles. The report’s methodology section says the score is the average of the fastest of at least nine timed laps, while the 1997, 1998 and 2000 bulletins carry a footnote saying the fastest twelve. With the individual laps in hand, the arithmetic answers it: every published average in this table is the mean of that vehicle’s fastest twelve laps, exact to the hundredth in all ten cases, which is consistent with both.

The human variable is also visible. Sergeant Pokora’s average is the slowest in seven of the ten vehicles and Sergeant Stevens’s in the other three, and the gap between the quickest and slowest driver’s average runs from about six tenths of a second in the Volvo wagon to 2.7 seconds in the Tahoe. The score is the average of the fastest twelve of the sixteen laps rather than a best lap; in five of the ten vehicles those twelve come from three of the four drivers.

Every item below is disclosed in the report’s preface rather than dug out of the data.

The Volvo sedan was retested, and scored on the worse run. The manufacturer felt the S–70 was not running correctly; the test driver and observer agreed. Volvo asked for a retest, it was granted, and the second set of results came out worse than the first. Michigan used the second set for the score anyway.

The automatic Camaro’s brakes were replaced. The pads and rotors on the automatic Camaro required replacement partway through the dynamics session, after two of the four drivers had completed their practice and timed runs.

The natural-gas car needed refueling. The CNG Police Interceptor required refueling after three drivers had finished their practice and test runs at the speedway; its tanks held the equivalent of ten gallons against the gasoline car’s nineteen.

Two Fords arrived with green brakes. The Explorer’s and Expedition’s brakes had not been burnished by the manufacturer before testing, so the report says their Phase II figures are “probably more indicative” of what can be expected.

Only one Camaro was braked. Because the two cars have identical braking systems and nearly identical test weight, only the automatic was submitted for brake testing. The 1997 and 1998 bulletins also print one Camaro brake row and give no reason; the 1996 book gives the same reason as this one.

Other conditions worth recording: every vehicle ran with a clean roof, no lightbar and no A-pillar spotlights, and the report says that once the emergency equipment is installed, performance “may be somewhat lower” than reported. The Jeeps were driven in “3” rather than overdrive; the 6-speed Camaro made its top-speed run in fifth. The Volvos’ traction control was switched off for dynamics and their transmissions were set to “S” for Sport.

The full report prints the scoring method in seven steps, and it is worth understanding because it is how the books that print it rank the vehicles.

Raw scores are recorded in each of the six categories in their own units — seconds, ft/s², miles per hour, points, miles per gallon. In each category the best-scoring vehicle becomes the benchmark and receives a deviation factor of zero. Every other vehicle’s deviation factor is the absolute difference between its score and the best score, divided by the best score. That factor is multiplied by the category weight — dynamics 30, acceleration 20, braking 20, top speed 15, ergonomics and communications 10, fuel economy 5 — to give a weighted category score, and the six are added together into a total weighted score. Lower is better: a perfect vehicle, best in all six categories, would score zero.

Then comes the part that makes these books a purchasing instrument rather than a magazine test. Michigan takes one percent of the lowest bid price received as its bid adjustment figure, multiplies each vehicle’s total weighted score by that figure, and adds the result to that vehicle’s actual bid. The vehicle with the lowest adjusted bid price wins — and the state then pays the real bid price, not the adjusted one. Performance doesn’t win the contract on its own; the best performer gets the smallest addition to its bid.

The report illustrates this with an example rather than the year’s real bids, so no bid prices are quoted here. The 1999 winner and the actual bid table are not in the published report.