Just how hard can it be to power portable electronics in an older BMW? Pop a USB car charger in the cigarette lighter socket, plug in a USB power cable, plug the cable into your device – and with that, end this ridiculously short and simple story. Except that in practice, the charger may not stay in and the cable may interfere with the shifter and nearby controls. To avoid these issues, folks have installed a USB power socket elsewhere – for example, in the glovebox or between the front seats – and hard-wired a USB charger into the car. Newer BMWs can come with built-in USB sockets, some of which fit an old E36 quite well. In particular, the USB/AUX-IN socket from the E90 3-Series fits into the switch cutouts in front of the shifter. In the most passenger-side cutout, it fits without the USB cable getting in the way.Here, I first briefly outline how I added a E90 USB/AUX-IN socket to my 1996 318is. I then go into the details and suggest some alternatives. The mod needs few parts, but there is perhaps more to choosing and installing them than one might suppose. What follows is just one man’s solution. Feel free to change and improve it to meet your needs and tastes.

http://www.unofficialbmw.com/john/e36_usb_power.html