Why most existing car chargers will not work with a new 3G iPhone

<BUMMER

Apple has removed the ability to charge the iPhone 3G via Firewire.
The iPods and original iPhone connector has two sets of power
connectors - one for USB and one for Firewire but the new iPhone 3G
only has USB charging pins.

Apple decided to completely remove support for Firewire charging on
the iPhone 3G, therefore certain accessories will not charge the
iPhone 3G.

Not all of them are incompatible with the iPhone 3G when it comes to
charging. Only those that were designed with the Firewire charging
ports.

Unfortunately because of the difference in voltages, 5V for USB and
12V for Firewire and the additional detail that cars operate in the 12
Volt range therefore almost every wired car kit uses the 12 volt
Firewire option to avoid changing voltages.

This is why they do not work with your new 3G iPhone.

/BUMMER>