We spent last weekend in the Park Slope neighborhood of Brooklyn, NY, visiting friends and spending a day at the Metropolitan Museum of Art in Manhattan so Tristan could see the Armor Room. The only dark spot in an otherwise enjoyable trip was that the passenger-side window of our Honda Civic was smashed one night while the car was parked on the street, and the power cable to the Garmin nuvi 255W GPS that we were borrowing from my parents was stolen.
Needless to say, we weren't so clueless that we had left the GPS itself, or any other valuables, in the car, so losing a $30 cable wasn't a big deal. Even having to pay $20 to park the car in a garage that night and $120 to have the window fixed the next day wasn't the end of the world. Everyone - from the people who drove by while I was leaving the parking space to the garage attendant to Joe of Joe's Auto Glass (highly recommended) - was extremely nice and sympathetic.
But the reason I tell this tale of minor woe is because Joe, with corroboration from others who have suffered similar misfortunes, told me that thefts of GPSes are exceedingly common in New York City these days - he had repaired 10 such broken windows that week. The thieves walk down the street looking for the tell-tale ring left on the windshield by a GPS suction cup mount, smash a side window, open the glove compartment, and remove any GPS left there. It's over in seconds.
So the moral of the story is, if you're leaving your car on the street in an urban neighborhood overnight - even in a nice neighborhood like Park Slope - take the GPS with you, hide both the suction cup mount for your GPS and the power cable, and clean the inside of the windshield to remove that subtle mark left by the suction cup mount. You may also be able to get a beanbag-style mount for your GPS - Garmin sells one that's compatible with the nuvi series that we picked up from Amazon.