As I mentioned in a previous post, I love spotting rare NYC yellow taxi cabs. And some of the rarest of them all is the small fleet of undercover NYPD cars disguised as yellow cabs. It's the perfect way to camouflage in this city. Just think about how many yellow cabs there are and how it would be hard to immediately distinguish a regular taxi from an unmarked NYPD vehicle. While the NYPD does have a variety of unmarked vehicles meant for surveillance and stealth, my favorite of them all has got to be the yellow cab range.

To most people, even New Yorkers, an undercover yellow taxi cab would be pretty hard to distinguish from a TLC vehicle since these NYPD cars also sport the 4-digit license number seen on all cabs as well as the highly-coveted taxi medallion stamped onto the hood.

But if you take a closer look, here are several ways you can tell you're looking at an NYPD car:

Look for a missing center divider. Undercover NYPD taxi cabs don't normally have the plastic divider separating the backseats from the front seat. Disconnected or fake meter. It's just for show and on some of these vehicles, the meter is missing completely from the dashboard. Grey bumpers. This one used to be an easy tell, but nowadays the vehicles have been updated to sport the regular yellow bumper. Extra black side skirts. This is another trait that has slowly been phased out since it made it too easy to spot to those on the lookout. A computer in the front seat. If you can get close enough, look for the NYPD computer mounted in the center console area in the front seat. 2W and 6Y. This is probably the easiest way to tell. All of the undercover taxis sport a license number starting with 2W and 6Y (important note: Not all vehicles starting with these characters are undercover).

In the photo gallery below, you'll find the following taxis: 2W97, 6Y19, 6Y17, 2W95, 2W68, 6Y13, and 6Y21*.

*It is possible that some of these vehicles have been decommissioned by the NYPD. But for historical and educational purposes, I've left them here for you to see.

All photos by Herman Yung/Doobybrain.com