Found this on a search for "cop Cars" on yahoo

The Link is
http://www.headgap.com/~Zenatos/Cop/massachusetts.html
and go here for ALL states
http://search.yahoo.com/search?p=cop+cars&toggle=1&ei=UTF-8&fr=FP-tab-web-t&vst=0&vs=www.headgap.com

Massachusettes

As of early April 1995, MA State Police have recently taken delivery of a
large batch of Caprices, which will replace a lot of the older Crown Vics,
and cause those who have memorized headlight patterns no end of problems.
They still have Mustang chase cars (5.0 both LX and GT); usually only see
these out west on the Mass Pike (I-90) or on I-95. Have also seen at least
one new model, unmarked, forest green Firebird, but not sure if that was
state or local unit. Have seen at least one Lincoln MkVII with grill
flashers but no lightbar. Marked vans and Blazers show up sometimes.
Occasional unmarked Econoline vans have been seen.

Massachusetts State Patrol uses nearly every Ford product. Vans, Broncos (I
and II), Explorers, Crown Victorias, LTDs, Lincoln Town Cars (they have 4 of
those, in different colors), a Mark VII, many Mark VIIIs of all colors, and
Tauruses. Dark blue (with grey section on marked vehicles) is the favored
color, but with the more exotic models, any color is possible. All marked
cars sport the low-profile strobe lights. Mass State Troopers also operate
Suburbans and Caprice Wagons. The state police now has a few green Chevy Z28
Camaros with the new Corvette lt1 engine. They have tinted glass all over
and blue strobe lights in the back window and blue flashing lights in the
front high beam of their headlights. Massachusetts now also uses the current
model Thunderbird LX and Camaro.

The Mass Pike (I-90) has their own troop of state police financed by tolls
and fines. They have an 'E' next to the identifying number on their
vehicles. Other Troopers on the Pike are usually (not always) just going
somewhere like you are. The Pike Troopers almost all have new, marked Chevy
Caprices or Crown Vics. They have a variety of unmarked types as follows:
brown, beat-up Ford van parks on shoulder
brown, Crown Vic, shoulder parker

Local town cops seem more evenly split between LTDs/Crown Victorias and
Caprices. Everyone uses low-profile light bars.

Most troopers in Mass. use Crown Vics, but there are also some Caprices and
even dark colored Taurus GL's. They are now using Chevy Camaros, too.

Hubbardston has none of the latest equipment available, but they do have a
95 and 93 Crown Vics which can't be missed with the gray blue and yellow
paint jobs.

Other notables: A cream and a burgundy Cadillac Seville STS, a Monte Carlo
SS, a red and black 1995 Camaros, a black Chevy Tahoe, and Harley Davidson
motorcycles in the Boston area.

1. Marked cars are: Grey and Navy. MOST are Crown Victoria's (in the eastern
region) with external light bars. MOST have "State Police" in reflective
letters on the trunk.
2. Many have internal lights on the rear parcel shelf with massive grill
lights. Many of those DO NOT have the reflective "SP" on the trunk.
3. There are Caprices in use, similarly marked.
4. In the eastern region there are a number of unmarked 5.0 liter Mustang
LX's in (one in Dark Grey and and one in Blue). ALSO there are Camaros (a
Red one and a Navy).
5. In central and western MA, there are marked and unmarked Tauruses in use.
6. Other vehicles: motorcycles, full size Bronco's and Econoline Vans
(marked and unmarked).

In the Boston area, there are some unmarked new Ford Mustangs