Due to the long cabin, the concept Eurocopter RB309 (Requin Blanc = White Shark) can fit up to 12 passengers in. This is how maximum efficiency is guaranteed. Moving more people in less time with lower costs.
 It has all the advantages of a helicopter: You can take off and land vertically. So a takeoff runway is not necessary. At the same time it can transform into a plane. By doing so, there is no maximum speed limit like there is physically for helicopters. 

The diesel-engine in the back gets cooling from the Fin-Lamels, since the air stream is travelling around the vehicle, especially on the sides to transfer the heat to the outside.