The Swiss from Rinspeed have always surprised us with their creativity in the automotive department. This time they announce the Dock+Go mobility concept, a two seater electric smart which could be attached with a third axle on two wheels when desired.
This concept which Rinspeed calls "backpacks on wheels" will be showcased at the 2012 Geneva Motor Show in March, and if you are a bit confused, the company’s boss says it should be regarded as a solution for various activities. For example the rear detachable section could turn this thing into the ideal mini car for any pizza delivery driver, as it can accommodate a heated box, while craftsmen could use it to organize their tools.
Golfers, skiers, etc. would also find the Rinspeed Dock+Go section useful, while the car’s 120 Km operating range could also be extended by turning the rear section into an energy pack fitted with either a combustion engine, a range extender, a battery pack or a fuel cell.     
The energy infusion is possible due to the fact that the docked third axle drives the rotating second axle. 

Source: Rinspeed