Long story...

I recently upgraded from my old junky car with Empeg to an X5 sans Empeg. I could not imagine doing any dash mods to the X5 for the empeg so I got an aftermarket bluetooth/ipod hookup that installs behind the OEM headunit, but I just hate using an ipod in the car. My cars have almost always had an empeg lovingly nestled therein. That's just what I expect to interface with when I get in the car. So...I started thinking about wifi in the car, empeg installed in the back, long cables, etc. I planned to use my Android app as a remote and have the phone associate with the AP when I got in the car. However, if my phone joined the car's network, then I would lose the data signal on the phone unless I had a 3/4G modem sitting on the wifi router as well. And I was not about to shell out an extra monthly data plan just to have remote control capability over my player...plus, I work from home and am not in the car that much.

So...I started toying around with the hotspot functionality of Android and quickly found out I could proxy wlan clients bound for the internet and have access back into the locally created wifi network as well.

I also started looking for some kind of wifi router with an RJ45 port that would work well in the car. I found this. It's otherwise known as an MPR-L8 and perhaps a handful of other names. Anyway, it's quite a remarkable piece of kit and we should probably all have one or two just for fun. It even has a battery that will last for 3hrs. I was able to plug in the Empeg via RJ45 and then get to it via wifi from my phone easily. Next, I tried putting the MPR-L8 into client mode and then getting it to connect to my phone, which was in hotspot mode. Victory! I able to surf the net over 4G on my phone while using the Empeg Remote app to control the player.

This led me to create another simple phone app which listens for the existence of a specific SSID e.g. "The Car Wlan" and, upon detecting it, slip into Hotspot mode. The MPR-L8 will then automatically associate with the phone's hotspot and at that point I've got 3/4G data to/from my phone as normal, but also have visibility back into the local wlan where the player is. voila!
This process takes about 30 sec from ignition.

This little app also keeps pinging the wlan for the existence of the MPR-L8 so that when I turn the car off it kills the hotspot and returns to whatever data mode the phone was in prior.