The names of the cars which leave the BMW factory have always been the same. We have the x-Series models, the X models and the Z ones.
BMW plans on introducing a new name in their line of vehicles, starting with the BMW X1 Concept. Every BMW which has a rear wheel drive will have BMW sDrive attached to whatever its name is. This name change might even be applied to the famous BMW Z4. The X1 concept will be available in two different versions, xDrive and BMW sDrive. Some people don’t agree with this change, but the difference is not that noticeable and the name is very suggestive.
We can suspect that BMW will be making front wheel drive models, rear wheel and four wheel in the future and the sDrive name is just a good way to be clear about the specifications of the vehicle.