Is the commonly assumed UFO (flying saucer) design aerodynamically efficient? Is this design, a circular disc (or flying saucer) slightly humped on the top and bottom aerodynamically efficient? And if, we are able to use it for commercial purposes , would they give a better efficiency than existing aircraft?

This article states that this would be a better design. Is this true?
They use the concept of VTOL thats vertical Take off and Landing. Click here to know more about VTOL

Regarding the efficiency, well I think no one can give a 100% perfect information on this because, we do not know the fuel used, the engineering behind the structure. There are a lot of factors affecting efficiency like :
Materials, Fuel, Type of Engine, Weight etc. So aerodynamics alone cannot judge the efficiency of the aerovehicle. 
Thanks!