That doesn't sound familiar..I live in CT and I'm all over the state. My wife's from Milford, near Shelton, and I've lived in that area. Has to be a Statie from a barracks in Western CT or a local...NEVER seen a MM in the shoreline/central CT, northwest Hartford area (pretty much my stomping grounds).
Previous unmarked included those mentioned. A couple years ago they went with 1 or 2 fully marked/white Vic's but I'm not sure if they got the results they wanted (higher profile...the state as far as I know has never had "obvious" cruisers running around with anything more than a few antenna's and a light bar). The most common vehicles for the CT State Police includes Intrepids, Impalas, Expeditions (the "4XForce") and 'Vics. They've been around 2-3 years, the Vic's MUCH longer. Never seen the state run Caprices (maybe DMV did/does, they hang out at the scales on 91 and 84).
I live right near the Dept of Public Safety (their HQ), and normally the cars are introduced to the media there (last time I saw was all published in the Hartford Courant). Guess it keeps the playing field level if you are willing to read the news. I drive by the parking lot every morning and have never seen a Mercury in there...
With budget problems like anyone, the DPS is primarily spending funds on hiring a mandated minimum amount of State Troopers (level's we've never had apparently, something like 1,200) and not new unmarked cars.
Maybe a siezure that some lucky sole get's to enforce with...hafta keep an eye out for him...wouldn't ordinarily think of another MM as the law...
JWM