I have several issues related to car charging:

1. I have the DC-6 car charger; the first one I had stopped working after a week - literally went up in smoke. I got a replacement, but note that it is running very hot - not usual for a car charger. If anyone else has the official DC-6 12v car charger from Nokia, check to see if the round portion that plugs into the car is running warm or hot.

2. Not all 3rd party chargers will work with the N900. I tried a clever, tiny USB jack that barely protrudes from the cigarette lighter jack in the car. Using a known good USB cable, the N900 refuses to charge. This is the Beljkin Micro Auto Charger for the iPod, F8Z446.

Using another generic micro USB car adapter however did seem to work.

3. My Nook and Kindle readers use the same micro-USB connection. Their AC chargers will charge the N900.

4. The N900 doesn't always recognize the Nokia AC charger. Unplug/replug is sometimes necessary.

My conclusion: I did read the other thread concerning the need for smart chargers. I'm just a little concerned that the official DC-6 from Nokia runs very hot, and I already had my first one go up in smoke. I have yet to try the Nokia CA-146C converter; I did see another note about one of these going up in smoke, too.

As for the FM transmitter - I have not had much success using it in the car, so I have been using the 3.5mm headphone jack to connect to the car audio system. I know the FM transmitter is working, since I tested it with another desktop radio. The signal is simply not strong enough in my car - whether using the charger, or not.