A police package, orderable under GM’s Regular Production Option code 9C1, was introduced for the new base-model Caprice that replaced the Impala for 1986. In the 1986 Michigan State Police tests, the Chevrolet Caprice was competitive with the Ford LTD Crown Victoria, Dodge Diplomat and Plymouth Gran Fury. The Caprice had the fastest quarter-mile times of the three, and the best fuel economy. The Dodge and Plymouth outran the Caprice in the 0–100 mph times, but placed last in the road course times. However, there was only a 1/3 second difference between the fastest and slowest vehicles on the road course. All four cars were very close in competition for 1986, and there was little performance difference.
For 1987, the 9C1 Caprice changed little. The 350-4bbl engine received a boost in compression, roller lifters, and new center-bolt valve covers. The 180 hp rating of this engine helped boost the Caprice’s performance above its competition. The 4.3 L LB4 V6 engine remained available, but was marketed towards urban police departments with less need for performance. Michigan State Police tests had the Chevrolet Caprice beating its competition from Ford, Dodge, and Plymouth in almost every category. The Caprice had the quickest quarter-mile times and 0–100 mph times, the highest top speed, the fastest road course time, and the best fuel economy, though the Plymouth and Dodge had shorter braking distances. The 1987 Chevrolet Caprice won the contract for the Michigan State police and would hold this contract until 1996 when the Caprice was discontinued.
For 1988, the 9C1 Caprice was again unchanged. Michigan State Police tests proved to be more competitive, with the Ford LTD Crown Victoria showing a strong improvement in performance. The Plymouth and Dodge models continued unchanged and were not competitive with the Chevrolet and Ford. 1988 tests showed the Caprice with the fastest quarter-mile and 0–100 mph times, the best fuel economy, the fastest road course time (although it tied with the Ford) and the best ergonomics. The Ford edged out the Chevrolet with a 1 mph faster top speed and better brakes, but the Chevrolet scored second place for both those categories. Overall the Chevrolet scored the highest in the competition, followed by the Ford, Dodge, and Plymouth.
For 1989, the 9C1 Caprice received some major changes to the drivetrain. All engines were now equipped with throttle-body fuel-injection (shared with the truck/van lineup and based on the LB4 4.3L TBI injection system first used with the 1985 model year passenger cars), and the 305 cu in (5.0L) engine (RPO LO3) was now added to the options list. The available engines were now the 4.3L (260 cu in) V6, the 305 cu in (5.0L) and 350 cu in (5.7L) V8s (which was only available on police package models). The V6 and 350 engines were equipped with TH700-R4 transmissions while the 305 engine used the TH200-4R transmission. The V6 and the 305 used a 3.08:1 axle ratio, while the 350-powered cars now used a 3.42:1 axle ratio. The 4.3L remained at 140 hp, while the 305 TBI engine was rated at 170 hp, and the 350 TBI engine was rated at 190 hp. Unlike the LO5 used with the GMT400 light-duty truck and van line including the R/V series, the police spec LO5 used the roller camshaft sourced from its TPI equipped F bodies and Corvette along with high flow fuel injectors. The 350 powered Caprice did well again at Michigan State Police tests for pursuit-rated cars. It had the fastest 0–100 mph, the fastest road course time, the highest top speed and the best fuel economy. The Dodge Diplomat and Ford LTD Crown Victoria outbraked the Caprice, and the Plymouth Fury and Dodge Diplomat had better ergonomics than the Caprice.
1990 was another carry-over year for the 9C1 Caprice with the only major change being door-mounted seatbelts. In Michigan State Police tests, the only competition was from the Ford LTD Crown Victoria, as the production of the Dodge Diplomat and Plymouth Gran Fury had ended during 1989. The Caprice won all six categories for 1990, having the quickest 0–100 times, the fastest road course times, the best brakes, highest top speed, the best fuel economy, and the best interior ergonomics. This was the first time any car had won all six categories in Michigan State Police tests.
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