Ah, the hub motor. Ford and GM have tested this idea with vehicles that used all four wheels as hub motors, but we have yet to see them used in production (granted this might be because so few electric vehicles are yet in the market). Although the hub motors have a relatively low Horsepower (HP) per wheel, there is no loss of power through a would-be power train, as the motor literally is the wheel. Additionally, as is the case with all electric motors, torque can be anywhere from 100% to 200% of the HP of the motor and is always available.
The trouble with the hub motor is the not only the added weight at the wheel, but the necessity for additional strength against the frame of the vehicle. Dipping into physics slightly here, when the engine, via the drive shaft, sends power to the wheel, the ground effectively pushes back on the wheel. The engine must overcome the force that the ground is exerting on the wheel (aka static friction) in order to move the vehicle forward. Most of the strain of these forces is handled by the strength of the drive shaft, but in the case of a wheel hub motor there is no drive shaft. The force that the ground exerts to resist the forward motion of the wheel hub is directly handled by the frame holding the wheel. If the frame is not reinforced, not merely to deal with the added weight of the wheel hub motor but these additional forces of ground resistance, it will cause a failure.
Now, as these students believe that they have a solid solution, and I am inclined to think that they have, the advantages of this idea are superb. For a relatively low cost of parts ($3000) and a small battery, it is possible to increase the efficiency of your current (non-hybrid) vehicle from 50% to 100%.
Check out the Original Article from Wired