I bought a Garmin Nuvi 1490TV around a year ago. The car charger that came with it, while fully adequate, had a rectangular strip about a couple of inches long which housed something which must make it different from any other normal mini-USB charger. The strip then promptly started breaking up (it is just two bits of plastic clicked together with a circuit board in the middle). Especially so as the cable is overly long and the strip hangs around where the vents, radio, air con controls etc are.
Inevitably it broke, I taped it together and it ran for a few months more and then gave up a few weeks ago.
I ordered a cheap one on eBay that promised compatibility but did no such thing although it is was mini-USB. Without the important bit in the middle, it just thinks that it is connected to a PC and goes into synch mode.
I ordered this one after reading the reviews and I love this one!
Whatever circuitry is needed is built in in the little round thing near the cigarette lighter end probably. The end bit is nicely curved so the cable doesn't tug (unlike the one that came in the box), actually says Garmin on the charger and just looks solidly built, works well and is a great price!
5* product, great delivery time and price.
Go for it if your Garmin has a mini-USB connector.