This setup means that when the wheels rebound, there is also no camber change which is great for traction, and that's the first advantage of a de Dion Tube. The second advantage is that it contributes to reduced unsprung weight in the vehicle because the transfer case / differential is attached to the chassis of the car rather than the suspension itself. More recently deDion suspension has had somewhat of a renaissance in the specialist sports car and kit car market such as those from Caterham, Westfield and Dax. These all uniformly now use outboard brake setups for ease-of-use... a well set up deDion system can often match it turn-for-turn now, especially for flyweight cars.

A de Dion tube is an automobile suspension technology. It is a sophisticated form of non-independent suspension and is a considerable improvement over the alternative swing axle and Hotchkiss drive types.

http://en.wikipedia.org/wiki/De_Dion_tube