Hmm can't think why it woudn't be.

The DVD's only have map data, nothing else. Its the car & the software it has which allows it to interpret it differently.

We're talking new 7 right? Because if it was an E38 (previous model 97' - 02') there is no question about it, that would work 100%.

Be carefull, some of the early E65's (new gen 7 series) come with CD drives and CD drives require CD maps (same goes with early X5's having CD drives). Later 7's and later X5's have DVD drives.

I say just put your nav disk in his drive and see what happens. Your not going to destroy either of your drives by doing so. If it doesn't work, it just will not. Or why don't you take a picture of the drive and post it here. That would help a lot...