$1600 with airfare, lodging, car rental, and obviously your planning and organizing talents included? You pay for your own food and laps- where does fuel factor into that? Included or an even split between the two people in each car?
I've wanted to do a trip to the Nurburgring for some time now, even tried to talk a friend into going and doing something similar, sharing a rental car. Let me work on the $$$ side of things and talk to my friend about it again and I'll get back to you.