Having just watch the internet movie Flying the Fish about a couple of friends who fly their microlights from Cape Town to the Fish River Canyon in Namibia, it lead me to think about overland trips that served a purpose i.e. the vehicle became a means by which something else was achieved.
My first example is Kingsley Holgate and his Outside Edge Expedition. In all of Kingsley's expeditions, vehicles become key to delivering a scroll of peace, or carrying a cargo load of anti-malaria mosquito nets. His vehicles are well equipped, driven hard and all have endless stories to tell! Youtube have plenty of videos relating to Kingsley Holgate. A favourite is his talk on behalf of the David Rattray Foundation:
A second trip springs to mind - The 1998 London to Sydney Overland Expedition. I am still uncertain if they actually flew the microlights but the idea certainly was to take them along.
A third trip that I thought was unusual was the Pizza Delivery team. This trip, more of a challenge, lead the team to ride motorbikes from South Africa North to deliver a pizza!
There are many trips who have used the Overland journey as means of raising awareness for charity organisations. I would attempt to list them all but it would take me ages to sift through the full list. A few charities spring to mind - Anti Land Mines, Malaria, Children and farming - to name a few.
Thinking outside the vehicle, I wonder what other unusual overland trips people have accomplished by using a vehicle as the base for the expedition.
A few alternative ideas that spring to mind:
Mapping Africa - Tracks 4 Africa have already started this and are doing a stirling job.
Flying - following a full Trans-Africa trip that uses a paramotor, microlight or gyrocopter
Sport - Travel through Africa linking up with local sport teams.