[E90M3CDFR]

I finally tried to back up the music I have stored on the HDD of my car's iDrive and I'm finding that it takes so long that even with a 2-3 hour drive (about the max with the size of the M3's gas tank) I get to about 50-60 percent completed before I have to stop to gas up. When I stop, I turn the engine off...and keep the radio/navi on. When I ignite the cylinders again, as it where, the back-up routine is prematurely ended even though the electrics don't appear to cut off (and the navi does not turn off/on, which conclusion is based on the fact that it does not prompt me whether to continue the guidance as it will if I cut off the system).

I have about 8GB of music loaded, so I'd really prefer to have a back up as I will soon be having the system software updated and the dealer said that this sometimes leads to the music collection being overwritten.

So two questions:

1) for those that have had the software on the CIC iDrive system updated, has the music on the HDD been erased/lost? and,

2) has anyone found a way to complete a backup to USB with a sizable music collection (6-8GB) off the HDD?

I've thought about leaving the car with the ignition on in the garage, but I'm concerned about the theft implications and the fact the electrics seem to cut off after a certain time period anyway and the only way to reset that cutoff seems to be to turn the engine on (which leads to the back up routine crapping out anywat).

And I'm of course assuming that a restore will work...but who knows?

Input much appreciated.