Quote: Originally Posted by
GlynHarper 
Got mine working finally! You do need to power the interface it turns out.. no matter whether it's USB or Serial.
As for which one. It really depends which PC you're going to use. If you have serial port, you can get the serial one. If not, get the USB one.
The USB one is just a USB/serial emulator anyway, so it should work with any setup.
I went for the USB one as it means I will always be able to use it, even if I change my laptop in the future and only have USB.
I have a Resler USB version that works fine on USB power alone. Just the IBus wire connected. When I had it powered via the CD changer connector I had strange behavior such as no clicking sound on directionals, no seat belt alarm, random dash lights (door open when it wasn't, trunk//boot open when it wasn't, etc). Powered only on USB everything works as expected.
(edit: my E46 is a 2000 323Ci (US))