I believe ibrennan is correct.
The insurance you get in Europe covers the car while you're driving over there. You do not put the car on your insurance here in the US until you take delivery from your dealer. In the interim between when you drop in off in Europe and take redelivery in the US the car is covered by BMW.
Current: 2013 Monte Carlo Blue F10 M5 (ED on 9/1/12), 2014 Anvil Willys Wheeler Jeep Wrangler (weekend toy)
Previous: 2009 Carbon Black E60 M5, 2006 Silverstone II E60 M5, 2003 Sterling Grey E39 M5, 2000 Anthracite E39 540i6, 1998 Jeep Grand Cherokee 5.9 Limited, 1990 Eagle Talon TSi AWD, 1978 Mazda RX-7