It's a gruelling enough trip across the desert in a 4x4 – let alone a 12-year-old Volvo.

But a mental health support worker, a decorator and an aero engineer are setting off from the Fens to cross the Sahara on a 4,500-mile charity rally.

Ferdie Pick, 32, his 28-year-old brother Ptolemy and their friend Danny Eves have set their sights on making it to Mali, via France, Spain, Morocco, the Western Sahara, Mauritania and Senegal.

If it survivives the journey, the Y-reg Volvo – which has had one or two owners in its time and clocked up more than 100,000 miles – will be auctioned off to raise funds for a medical centre.

'We're not going in a 4x4. We're going in a Volvo S60T we got for �1,500 with about two inches of ground clearence,' said Mr Pick, from Stoke Ferry. 'It's got a roof rack and a reinforced underside because the roads out there are really awful –there are so many rocks.

'A couple of presidential flags on the wings and we're ready to go.

'We have no support, there's no back-up truck. All being well it'll take us three weeks.'

Mr Pick, who works at the Fermoy Unit in King's Lynn, said the trip would be something of a personal milestone.

'After having a very boring, uneventful 2011, I couldn't bear for 2012 to be the same,' he said.

'I need a coming of age trip, something you can't buy.

'So I looked for a charitable challenge where I could channel my energies. I wanted to do something for a hospital or medical type charity.

'After hours looking at stuff on the internet I was taken aback by this crazy idea.'

The trio – who all attended Downham Market High School – will be setting off on January 3 or 4. The rally was originally known as the Timbuktu Challenge, but the route has been changed to end in Bamako on Foreign Office advice, because of tensions in the region.

After travelling through Europe on their own, they will meet others taking part in southern Spain. From there, they will catch the ferry across the Mediterranean to Tangiers, in Morocco, before setting off south in groups of five vehicles for safety.