In conjunction with this thread and this thread:
I'm going to have to add to SC's list of undercover vehicles. It appears someone at work blew by a black unmarked Tahoe with tinted windows and ultimately recieved a ticket for 15 over the other day.
I've seen Tahoes and Suburbans pulling over semi-trucks plastered with "SCDOT TRANSPORTATION PATROL." Or something to that extent on the side. But now it appears they have other uses.
Greenville County and now our State Patrol have moved rapidly to Impala's for traffic patrol. So I guess the lesson we're learning is not to judge a book by it's cover but ask "Is it American?" and "Are those tints insanely dark?" Even if the license plate is a standard civilian issue, who knows!
So if it's been working for another state, or even another juristiction of government like the FBI, and it looks official with tinted windows, don't take any chances.