The replacement of the internal combustion engine and drive-train with electric motor(s), batteries, and control systems is leading to a rethink of the way in which cars are designed and manufactured. One of the proposals, which dates from the turn of the last century, is the hub motor, an idea originally put forth by Ferdinand Porsche. Because hub motors can deliver power to each wheel independently, four-wheel-drive becomes the default design; plus, stability and traction control can be built-in. Hub motors also save space and weight because there is no need for a mechanical transmission, drive-shaft, or differential. It will be interesting to see if this concept becomes the design standard for electric cars.
An overview of this design strategy can be found at http://www.economist.com/science-technology/displaystory.cfm?story_id=15949099.