The memo states that "due to upcoming U.S. regulations in effect for Model Year 2009, we are changing some of our naming protocol. The new naming protocol will affect all products that currently have an engine displacement designation within the name—X3, X5, X6, Z4 and Z4 Coupe."
It is uncertain whether the Z4 will also get the 'Drive' suffix, but it is expected that the X3 and X5 will follow the same conventions as the X6 and have 'Drive' placed before the engine displacement number.
At the end of the day, the new naming protocol will have little effect on the cars, but the xDrive badge on a car never looks good in our mind - we're predicting a raft of debadged models driving around in the future.