Well, mine quit on me on the drive home yesterday. It's fairly hot out, above 90F, but I do use a windshield sun protector and put a white baby sock over the 0803 and the windows cracked when parked. As soon as I started the car I had the a/c on 'defrost' to blow cooler air up the windshield interior first for a while, to give the camera a little better ambient as quick as possible.
It was hot to the touch when I got home and realized it had quit, but not to where I couldn't dismount it. After I let it cool off inside a little while it did respond to the power button, but the screen almost immediately said 'low battery' and shut off again. So I'm guessing either the contacts got loose and it wasn't charging and shut off (mount problem), charger died or got loose in the accessory socket, or the electronics just plain overheated and shut off, or I have a bad battery (or some combination of above).
Very recent purchase with the June 2014 firmware already on it from a guy who claims it was in a shipment to him on 25 July (ebay seller nuasys), so probably does not have the heatsink mod. Popped the 2 little screws on the mount and the interior does not look like daedelus's video...on mine the circuit board is mounted to the top removable part of the mount and there are lips underneath so no clear way to just do a paper shim. Might be able to paint an even layer of nail polish or something on the raised ridge where that part seats to add an equivalent shimming thickness, but will wait to try that another day; this morning just going to try and verify all connections and that it records again (morning temps around 80F).
Will update if I come to a conclusion. Yesterday was not near the peak temps I live in, so definitely need this sorted.
EDIT : Worked OK on hour commute this morning; verified the charger light was on (and firm in socket), mini-USB plug was firm in the GPS base mount. Started up fine with ignition and doesn't appear to have bobbled at all. So starting to rule it down to inconsistent mount contact, overheat shutdown (like sila is mentioning...TX conditions are quite similar and I can't do much about direct sunlight on the unit while driving), or bad battery which might also be overheat related. I might be swiss-cheesing mine soon.
