I can certainly understand your feelings. Having a 5 series is nice, but not the same as taking delivery of your own car. I'll echo the last post - postpone your trip?
But no matter what, you'll have a blast. Let me assure you that BMW will treat you like royalty at the Welt, and it'll still be a day you won't forget. And Germany is a blast. So while you'll be missing out on a piece of the pie, you're still getting a good chunk of it.
And there is one upside: I couldn't drive my car over 100 on the Autobahn, cause of the break-in period. But you won't have that issue with the loaner. So all I can say is, drive that 5 series like you stole it!
